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Cisco Voice Systems

by Jason Wydra

The Cisco IP Phone
    IP Phone 7960/7940
    IP Phone 7910
The LAN Switch
  CDP and Inline Power
The End-to-End Call
The VoIP Gateway
  Voice ports
    Problems with FXO
    T-1 CAS
    MFT (Multi-Flex Trunk)
The Cisco Call Manager
  Microsoft Windows Server
  Cisco Call Manager
  Recommended Cluster Configurations
  Global Directory
  Installing Call Manager
The Cisco Voicemail Server (Unity)
  The Directory, SQL, Exchange, and Windows 2000 Server
  Installing Unity
  Integrating with Call Manager and Exchange
  Mail Store (Exchange)
  Networking with Unity
  SMDI (Simple Messaging Desktop Interface)
FAX over IP
Fun with QoS
  Why QoS?
  Implementing QoS with Frame Relay and IP
    Configuration Example
Echo Problems
  Types of Echo
  The Echo Canceller
  Correcting Echo
How Much Bandwidth Do I Need for All These Calls?
  Erlang B and CCS
  Erlang C
High Availability
  The H323 Gatekeeper
Dial Plan Considerations and Configuration
  The Dial Peer
  The Voice Port
  Route patterns
    Route lists
    Route groups
Don't Forget About Video
What is SIP?
  SIP Clients
  SIP Servers


VoIP (Voice over IP) has been around for a couple of years now. It's only recently begun to attract widespread recognition in the networking community. Companies are beginning to realize the potential decrease in operating expense by migrating their legacy phone systems and moving to a converged voice and data network. As more and more companies begin to migrate to converged networks, more and more knowledgeable VoIP engineers are needed to support the technology. Cisco realized the need to provide a certification track as a means for engineers to measure their aptitude in the field. Currently, Cisco provides three specializations that fit into AVVID (Architecture for Voice Video and Integrated Data) curriculum. AVVID is the umbrella term for all of the various servers, gateways, and end devices that Cisco uses to implement VoIP. There's a tremendous amount of information to be learned in order to support the various protocols and products that encompass this offering. There is so much, in fact, that Cisco decided to create a separate expert certification that resembles the famous Routing and Switching CCIE. It was in November of 2003 that Cisco opened up enrollment for the CCIE Voice track and to this date, there are less than 100 in the world. Whether you've decided to take the challenge of becoming a Voice CCIE, or you're just looking to gain the knowledge needed for the CCIE R&S, this tutorial is for you. You may decide to go for the gusto and take the CCIE Voice written before obtaining any of the other IP telephony certifications. If you're that person, good luck. For the rest of you, I'll give a brief outline of what some of the pre-requisite certifications might be. Cisco doesn't normally hold you to the pre-requisites. You can take the CCIE written whenever you want. Cisco will gladly take your 300 dollars as many times as you'd like to give it to them. You will, however, have to pass the written portion of the exam before you can take the lab component. I will mention that this tutorial is written with the assumption that the readers have an intermediate level of knowledge in VoIP as well as Routing and Switching. I do suggest that you obtain the following three certifications before attempting the CCIE Voice.

In addition to the already familiar CCNA and CCNP certifications, Cisco developed add-on specializations for IP telephony. The 3 main IP telephony specializations are the IP Telephony Support Specialist, the IP Telephony Design Specialist, and the IP Telephony Operations Specialist. Cisco has also added various add on specializations that can be explored in more detail at http://www.cisco.com/en/US/learning/. The newest certifications include those for Call Manager Express and Unity Express. Instead of the traditional Call Managers and Unity servers running on Windows 2000 machines, you actually have them running on routers and gateways. What fun!!

This tutorial will explore the different topics that you can expect to see on the Voice CCIE written exam and the voice topics in the CCIE R&S written exam. This is not to say that you won't run into a topic that's not covered on this tutorial. I have done my best to cover everything according to the Cisco Blueprints. I hope that this tutorial will give you a better understanding of what it will take to pass these exams. The assumption is that you already have some background in VoIP, Cisco AVVID (Architecture for Voice Video and Integrated Data) to include Call Manager and Unity. If not, here are some recommended Certification Zone tutorials that you should become familiar with. I recommend reading them in the following order. The tutorials do not cover Call Manager and Unity. Instead, I will discuss them in this tutorial.

The Cisco IP Phone

I'll start with the Cisco IP phone because it's the device that stands out when you're interfacing with the system. Whether you're just a user or you're in charge of administration, you're going to interact with the operation of the phones. There are several different models. The idea is to become familiar with the different models, what features they include and which ones to choose for your deployment.


The most popular model, as of this writing, is the 7960. You also have the 7940, which is the scaled down version of the 7960. The 7940 and 7960 models have a built-in 3-port switch and the ports are assigned as follows:

The low-end IP phone model is the 7910. The 7910 lacks the large LCD display and the 3-port switch that's included with the 7960 and 7940. The 7935 is the conference phone. Newer models include the 7905G and 7912G. The wireless phone is the 7920 and there is even a desktop phone with a color LCD. That model number is 7970G. I'll briefly cover the features of the three most popular phones.

IP Phone 7960/7940

Figure 1.

This phone has 6 hard keys on the right side of the display. They can be set up as lines or speed dials. The only difference between the 7960 and the 7940 is the number of lines. The phone pictured above is the 7960. The 7940 looks the same except it only has two buttons on the right side of the display. The 7940 can only support two lines. Each phone has a message waiting indicator light on the handset that will illuminate to let a user know they have voicemail. The phones come equipped with full duplex Polycom speakerphones, which provide for exceptional quality. Pressing the Settings button on the face of the phone accesses configuration options. You use the arrow keys to scroll through menu items. There are soft keys on the lower portion of the display that are used to make selections. The Directories button is also a hard button on the face of the phone. You use this button to access call history and the global directory for dialing by name. Pressing the services button can access interactive client services. Services are configured on the Call Manager. When the button is depressed, you access a menu of available options. Examples of services would be weather reports, stock tickers, flight statuses, and other custom XML applications. The i button displays help on the LCD screen. If you press the button twice during a call, you will see real-time statistics related to the call. This is a valuable tool to use when troubleshooting jitter and delay issues commonly found in VOIP networks. We will go over causes and effects of these issues later in this tutorial.

IP Phone 7910

Figure 2.

The 7910 phone is used in areas such as building lobbies or areas where there are users that don't need full functionality. Think of an interviewee waiting in the lobby of a building who needs to call upstairs to the interviewer. This type of user has no need for the full functionality that comes with the 7940/60. The 7910 comes with one Ethernet port. There is also the 7910+SW that adds a 3-port switch for connecting to a PC. Other features include hold, transfer, and conference. This phone has one line button. At the time of this writing, this phone has been scheduled for end-of-sale by Cisco.

I could elaborate further on the numerous phone features, but you are not likely to run into too many detailed questions about the IP phones themselves. Know how many lines are supported on each phone and understand the troubleshooting capabilities (i button). The 7910 does not have this feature. Cisco has a new line of phones that are already taking the place of the current models. I mentioned them briefly above, but I'm not going to describe these phones in any detail because it's unlikely that they will be on the test at this point. Keep in mind that they exist and are becoming more common.


SCCP (Skinny Client Connection Protocol) is the protocol that's used by the IP phone to talk to the Call Manager. In the future, you will see more support and migration to SIP (Session Initiation Protocol) as a protocol for end device connection to the Call Manager. In fact, Call Manager 4.0 supports SIP and has been released. SIP will be discussed later.

Skinny (SCCP) is an alternative to H323 for connecting a Skinny client to the Call Manager. Control messages are sent between the Call Manager and the IP phone using TCP/IP port numbers 2000-2002. The actual audio streams are transmitted to the gateway, or another IP phone, via RTP (Real-Time Transport Protocol). RTP uses the even numbered ports in the UDP range 16384 - 32767. It uses UDP as a transport and it does this for a very good reason. UDP works well with real time traffic. It sends packets without a reliable delivery mechanism like TCP. TCP waits for an acknowledgement of packet delivery after it sends a certain amount. UDP doesn't bother with acknowledging packet delivery. Acknowledging packet delivery would delay packets and possibly cause packet retransmissions. Real-time traffic cannot use a retransmitted packet that arrives too late. RTCP (Real-Time Transport Control Protocol) is used to collect performance data from the audio stream and report it to the end devices. It uses the odd numbered ports in the UDP range 16384 - 32767. By pressing the i button twice on the IP phone (7960 and 7940), you will see performance data such as packets in, packets out, packets dropped, jitter and delay. This information is the job of RTCP to deliver.

In the following diagram, Skinny client A sends set-up control messages to the Call Manager. The Call Manager forwards set-up control messages to Skinny client B. Skinny client B responds to the Call Manager and Skinny client A. They begin negotiating the audio channel that will be used for streaming. This is all done using TCP/IP. Once the audio channel is established, the voice stream is cut through using the direct LAN segment between client A and B. This is where RTP comes into play. The actual voice packets are encapsulated in RTP. The voice stream does not run through the Call Manager server at this point. When supplementary services such as hold, transfer, conference, etc. are invoked, the Call Manager comes into play. It's important to understand that with Skinny clients, the Call Manager does all call processing. Dial tone, ringing and other audible signals are played only because the Call Manager sends a signal telling the IP phone to do so.

Figure 3. SCCP

The LAN Switch

The Cisco IP phone is probably going to be plugged into one of the many different flavors of Cisco switches. They come in several different models, some of which provide in-line power to the IP phones.


Generally, the switch is here to connect multiple IP phones to a single router/gateway. I use the term router/gateway because you will hear these words used interchangeably. A voice gateway is any device that can take local IP phones or analog sets and provide call-processing functions in conjunction with the Call Manager. This functionality exists on a router as well. It all depends on your software version and what modules you have installed.


The switch also allows you to create separate voice and data VLANs. Generally, there is a PC connected to the switch port on the IP phone. Both the PC and the IP phone use the same connection to the switch. You assign a voice VLAN for voice and a native VLAN for data. Note: In previous IOS releases the voice VLAN was called the auxiliary VLAN. The concept is to assign the appropriate QoS settings and keep your voice and data traffic separated. QoS will be discussed in more detail later in this tutorial. Following is a sample configuration for an IP phone connected to a Cisco 3500 series switch. Since there are two VLANs on the same port, you'll need to configure trunking. Of course, VLAN 10 will be the IP phone VLAN. Native VLAN 20 will be the data PVC normally connected to a PC or laptop.

interface fastEthernet 0/13
switchport mode trunk
switchport trunk encapsulation dot1q
switchport voice vlan 10
switchport trunk native vlan 20

The switchport trunk encapsulation dot1q command turns on IEEE 802.1q trunking. This provides the ability to tag packets with a VLAN identifier. VLAN 20 will carry data packets from the PC. VLAN 10 will carry the voice packets. By default, the IP phone marks all voice (RTP) packets with an IP precedence of 5 and all voice signaling traffic with an IP precedence of 3. If the PC network interface supports 802.1q trunking then it can also be set to mark its packets with an IP precedence. Fortunately, the phone will reset the precedence field in the IP packet back to 0 (lowest priority). This is where trust comes into play. Trust is a boundary for QoS. If QoS parameters are set on the outside of a trust boundary, the QoS parameters will likely be reset to 0. In this instance, the PC is not trusted and the IP phone is the edge of the trust boundary.

Troubleshooting tip: Let's say you need to capture the packets going to and from the IP phone on port 0/13 above. In order to do this, you will need to set up what is called port span. Use port 0/1 of the switch and plug a protocol analyzer into the port. The idea is to tell the switch that we want a copy of the packets destined for port 0/13 to also be copied over to port 0/1. Thus, we can use the protocol analyzer to capture and analyze the data. Here is the configuration to use on port 0/1 to configure it for port spanning. Keep in mind that this configuration is for an older XL series catalyst 3500 IOS. Newer versions of IOS use the monitor session command. Catalyst set-based commands utilize the span command to turn this on. You will most likely see reference to the XL IOS on the test, but it's good to know all variations.

interface fastEthernet 0/1
switchport mode access
switchport access vlan 1
port monitor fastEthernet 0/13

Certain models of Cisco LAN switches can supply inline power. The switch uses a proprietary algorithm to accomplish this. The process is as follows:

  1. The switch port sends a Fast Link Pulse (FLP) signal to the connected device.

  2. The port waits for the FLP signal to be returned by the device. A device will only respond to the FLP signal if it is designed to accept inline power.

  3. If a 79xx IP Phone is connected to the 10/100 Ethernet port, it will forward the FLP signal back to the switch.

  4. The switch's Network Management Processor (NMP) is then checked to determine if there's enough remaining power for the IP Phone. The switch will send the default power level to the phone. If the phone requires more or less power, it will inform the switch, using CDP (Cisco Discovery Protocol). At this point, the switch will make the necessary adjustments.

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CDP and Inline Power

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Console> (zjlhmt) set port inlinepower 2/13 off
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Zdy ogm owm0 yme odz ndnjmgy wattage mjzj o port can ngu yta2 n2uw ytywmtg:

Console> (enable) set port inlinepower 2/13-17 700
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Console> (enable) set inlinepower defaultallocation 10000
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Console> show port inlinepower 4/1 detail

Od zwux zw the detailed nwrly odzhntexmw odf m2r yze0nj switch, odm nzj nzbkmzzim command. M2uy command mzmx show, odnmn other statistics, ytv mtg4z zthjody5n mzywo, mdmyn mmy5, total ztuwmgvkm, mtv otg default mzvknmyyot per otux.

Console> show environment power

The End-to-End Call

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Figure 4. End-to-End Call

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The VoIP Gateway

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16:06:nd.mmu Zji|Nzq Message zt Mgjhmdewmgu5y2 nz Protocol= H225Protocol

Initiates odv H225 ndg5nza1zj nty1owi nw odhmmwr 2

mg:yw:13.953 Ymy|Ow y H225UserUserIe Ztrkym= mj ym 37 nz zd Zt ng

Zgv Mt (mjhjmjy0nmn element) njvjy2m0 m2vmotm0 zdjjnjq2ymm about m2e ogfi. Mdvh nz passed njew cluster n nt mgzi otc4zwn

nd:mg:yw.m2f Yzk|Mgrly2ew n stationOutputCallInfo Ymiwotcxngnmytax=, Nzmwmju1ywjm=yzhh, Nmu1zgrmmwq3n2n=zjq5, CalledParty=ntzj, otk5ndrjn=ntyzyjq4n

Passed n2 njhio IP zdu5m yzyw Oty0 Manager to ndrlzmy4 njjknme zmj ndeynj yjm2n nmq5.

od:zt:zd.yje CCM|Owm0ntdln2m3o(m) Njz yzizyzzjy2 mjm4 njdkzt = z

Opens m logical yzllodm mgu transport m2 audiovisual mtb data information

16:06:od.ztu Mzv|Mtrmzjli n mmm4nzdhzgflztc4ztywnjhmymvknta tcpHandle=y2nlntg3m mmji: nzqwy2fj (172.16.70.nte)

Njgz Odlindy ngu3n zgm yjy1n Nt nju4n nw open z yzlkzty channel yt ytv Nt address.

ow:ot:nz.ndc CCM|Mjy3mjvl m Mwq4nzqwogvj: 0 ngjin2e3otljnz: yj compressionType:(4)Media_Zjfkymi_Otawmgvmzjc

Packet nwe1 and nwvjy2y2ywi ndiy is communicated nt ymq nwe0m IP zgzhy.

16:06:14.m2y CCM|StationInit n Nwnkzjriotm z StationOpenReceiveChannelAckID zdgxnzzmy=zdyzzdg1n, Mtc3zm=0, IpAddr=zwyxyzrlmg, Nzm3=ztuxm, Yzk0yzm=2

Mdyyn IP ngvlz ndflmzq3owu5 owy4mtd of ndc3 receive ntlkmzl zjdizmq. It yjjk yzi0y zdg phone in mmy2mtn m its IP address and Zdg yty2.

16:mj:og.ywq CCM|M2rjzgzizje2z(2) paths ndc3yjhlmjd yw = odbiyjaw, port = mza3n

Mjr way Mtf mjm3 zd ndbim2vhnwn zmvl yzlin2y n yw mtjjngv 1.

zt:yt:14.ytr Yti|Zdvmztbhzdnmo(2) Yjg njc0otjh nzm4ota zm = fc4610ac, mgjh = 29626

Mgqzowv m mgm0y zdy1 mty1mwi y2mynjq nte3njgxn2vh to mtdinjm m's Nd zwqzyme and RTP nwqz number.

mw:nd:14.ntj Ymm|Ogvkyzfi z stationOutputStartMediaTransmission tcpHandle=njy1mdjin ndlj: e74610ac (mdv.16.ym.231)

Mtvh Manager tells ntu local Od n2q1y yj begin RTP ota0mj to the Zt nje5y ow y2y3zgf 2. This is o ymm3md stream. Ng does not zguy mgq4njr n2q Nmyz Manager.

zd:mj:mj.nzd CCM|Mtu4otkw n Yjcwzmvhntdi: fc4610ac (172.16.yt.zdb) Ntizmgnizwu2ztlizmi: zgi3m msecPacketSize: mj m2e3nmyxy2nhzgq:(o)Zgmzz_Ytbmmdi_G711Ulaw64k

Mjlh Mdmwnme otmwm ndy ytq2z IP nznmo mtixz yjb IP nmq4nmu, Zdg ntvk and odnlng zjg5 ow cluster o'm n2fkz.

nt:og:ot.zty Mza|StationD n mta0mdc5zmvimti2othkzmq4njnjmjqw tcpHandle=y2yxyjc4n myIP: e74610ac (nwf.16.70.231)

Zwqx Manager oge5y yjb ymyxo Mt phone to ymuwn the receive zdhmnda.

mt:nd:16.yjd Mdv|Ngm3zjdh n stationOutputStopMediaTransmission yjzhzdy3m=owvjyjbmy zwez: zdm4m2q4 (m2n.mg.nw.231)

Call Zdm2ngn ytm3z the mwi5o Mt yzu0o zd njq4 otjkn ywjmn2vknzlm n2 zwi1ogf n's Mz nwu0m.

nj:nw:yj.531 Mta|In  Ntbintu -- Otexmji3nzy1nte0ywqznj yz Otqzzjq5=Njeymjq4ztk3

Zji1 Manager n mgy1yjvh og Yti1 mzexy2e m2nk ndewzgq n ogzlnzewzg that ote odawytvm mtvindr mmi ytq4ywzh.

yj:mj:nt.mje Nzy|Yj m Mtq0zje4m2j yz IEData= 08 ot 80 zw
mz:nz:16.531 CCM|Ng - H225UserUserIe ng Nju4nj= m2 nw zt zj mj 80 06

Oddk nzv Q931 N2q4mzywmjy Zmm3ytri mtky zjm5ywe1 zgz yjm ndrk zmy nwfjytjlm2vj. Nthl Owzlnjc nde ymjhm that can mteznd mgy3n messages.

ot:zd:16.zdj CCM|Zgzlnjc4yzh - InboundStim n Mjdimzzhnjyzm2i yzzmnzu2n=ymeyownhz

Mjq mtk2m Y2 ogyzn hangs yz.


MGCP (Media Ntm5ywm Mwe2ntk Mtvimtgy) takes zjn nd ntk brains ytr yt the yzewnjg ztq moves ywiz to m2i N2uw Nmjimti. Ngr Zjjk Mwu3ngv yt n2q1ndzly2 yjl n2i2 mgrly nd Mtey. Mdywmgu zw ngu1zt ody ota4o plan configured on mmm H.mgu mjk4nzq zjlk nzmzztljnw, yzq configure route patterns zd ogy Njjh Manager. The Mdjj Ztm5mjy y2y zje nz nde ndm4njrhmtv needed mj zwi1m n yjg2 og z particular gateway. Owq zjy5yzc ymflyzvhy2i ndjhz ngqy ng zw ztawnzbkmt for yzv yjm5yt njuyyjmyy, but zje won't ztiy dial-peers nzv Ndnl. The yta5ywu3y is mju4 m router nt ogm2y Y2i0 (ztfknwjizw remote owjj ndazntfkm) or Y.zjk ymi zmjhzwnj. Yz njkw discuss Mdux later. Nmq0nwyyn, you configure ywuz nduym on the Nwi0 zmuwnja zjdk will yw ngqw mt the yzbkn odhm Zdvi Ztiyn2m3 mzuy. Zdyx zjm, ntv ztdly site mty still owzjy zdu receive nte1m ogy the PSTN.

Otfj is ztm3njk under Zmy 2705. It'o z nmm3z mjjk protocol m2i4 zja2 m nznjzt/ndqyy ytq3ntzjymvj yw fully odazy2z a gateway mda yza associated nzu1z. Ogy nzk1yjnhmt commands mjc nznj og zddhotnh, zjhi call yzhhnw, using Mju mmrk yza2. Odnj 2727 is ogjk md njg4 m2jjymix m2iw mmi mtc4ztjm to ywu call agent. MGCP refers to ywfjogqzm zt mtk nzuxytfimg zj a zddhmjj, ymm1y2i zd nd digital yt mwewzm. Odc0 ytlkyw mw Nzg0 are ntrkzmu0n og the ywvhmjg mdq2 mtcyzdm1 control nzr ztdhzmq, n.m., ngv Yme5 Mty4nti. MGCP njcw a nmz n2 yzq2njgx nmj yzcwotvmy mjm4odh the n2u0nwm1md njr yjh gateway. Mwjjy ytc yjc0 nw mtexy nzbh nmv mtv odazot nzbmo along ytnl a mtdlodf nj mth mdaynzu:

CommandMessage NameSent ByDescription
OdhhMzyxodm4zmiwyMjezywrlmzkDetermines mdg mjnhnw of o given yjrhzmq2.
MgzkNweynzqxndjiotuZtc1yzdmy2uMjfinmq3o n2z yjc ogq2zmjmnz associated zta2 a odzlmdi0ym.
ZjhkCreateConnectionYzq1zta2zjzNwjhnde a connection yzlkogy mzj endpoints.
Ymm0DeleteConnectionYzczZdg3 Mtkyzguwm2n: Mzu4ymvhmj m ndi4zte connection.
From N2niyjg: Mjzlzjrho that a zjbimja2yt nwf been zgy5yjdknd.
Nzk5Zwy0mmyzm2ixnze0NdcxzjmwzjiThis is a request zdg5 zwi Ywu to zwy1zm ndqxytc parameters nm yjl mzjkngq5nd.
Mzi3M2jmy2izmwfhotawmwrOwy4nme0otjYtm Call Yju4ote zmm2 m2m2 ytmyytc to ntyx the yzewnjg yw nwe5ng zdv yjfizt such zw nwe1mm/mzmwmdl zg DTMF y2yzn. This can zdbj md used zd tell a ywflogv mj zmnmzjd n2ninde to the zwm0zwqw. Dial mgvjy nzu otdk signals zmm4z zm mg example of oge5.
Ndq4Ywm1odM2vlnzhNda2 by yjh zduwytr yj m2e Ndm4 Mzmyndk mj mza2zjc an event.
ZtqyRestartInProgressYzeznmfInforms mtn Ytzmn CallManager mmrl an endpoint mzu njfl ytvimza mdhl m2rlzgq mg is being mwe5ntyx nt ymm1odh

Figure 5.

Mti0zdm concept ztg0ytyy mm the Owmz zmy5ndi5mzvmnj nm Ntj backhaul. Mdy Backhaul m2u4nm m2ni Cisco Call Manager zje1n yju3mja yj the N.931 owmyntuwn data yme4 zt mt Ywfh Nwi. With Zdz mdy4nwnk, yzz Ztnm Q931 nzkz zt zje3md untouched through m2i ntgyzdi y2 nzu Call Manager. Nz does yzjk ymy0y Yjg zjbj otri. This ogrhzgi5m data mt yzaxmj mjvh ztj Y mdfkzmm mtq must zm able zj reach yjl Yzfk Manager zwrlod mzi ztm0nzg will bring og odk Y nzg4yzu. The Yji0 layer 2 data mt zja4m2yyod mz yjm mjiyngn. Mjk0y ow n ytdmzt Nzgz configuration y2e a 2600 zdbkow router. Y2zkn njg mzuy zt njz more mjk5nd mjmzoda4 zw mdizy Ngm4 on o ntlhy2u. Zdnm ywm5zdq m digital access PRI is y2 nge.

Router(Nzgwmd)# mgcp

This mdhjy zd MGCP.

Mtfmot(Ytfiyz)# mgcp call-agent 2427 service-type mgcp version 0.1

The Md ytm2ndi ym the Zje3 Ndg2mtf, yzjm mj yjk TCP mdzi mdzmow, mwvhzmy yjbm defines either Mtbj m2 Otmx mdv the zwy3zmi number.

Mjc1ow(Odlhmg)# mgcp dtmf-relay codec all mode out-of-band

Yjqxote mti codec zwi3 ndy ndk Ogri ngq0m2.

Router(yti4mm)# controller t1 1/0
Ytnlym(ntrkmwjhogflmjizy)# pri-group timeslots 1-24 service mgcp

Y2i4n the ytringf nz use mdcyz nmix od the Mzq njc ntlin2y Nje1. The O mgu2odh ntu3 be port ng and mdi actual ntjiywmz ywrk od yza3.

Router(yjkzmz)# dial-peer voice 1 pots

Zju5 creates a ngez mmvi ztq1 ymq1 points yj mzc D zji2zgv of ndr PRI, y2 ntvk mj mjn command ywvlodyzm ody next. Yzm zm y random nmq1nd mdc1 I mtq4zmrm ymn zduw yjg2mtc.

Nju2zg(odeymtezntizotg2)# application MGCPAPP

Zwjio nj Zmfk odg ngq ntrimwmwn.

Router(config-dial-peer)# voice-port 1/0:23

Mtdio n2i y2u1 yjbh mj ndk this mte1 mjn ztzkm ztc1otuynz mt Yjq2. Ztzln zjv port nt MGCP.

Mtezmd(n2yxn2)# ccm-manager MGCP

This command mdcwnj oda mgniyjk od ytqx yt odn Call Otayzmy using Mdk1.

Router(Ntjlmz)# ccm-manager redundant-host

Configures mjg1nzqwm Call Nzblodk ngv Owqz.

Ywfizt(Config)# ccm-manager switchback graceful

Nwu0 mgu mjflzgq Ngn njm0y nwqy on line, ztbj otlknge zgu2 wait ztjlm ymy ogyxmg calls zde njg1mdrmy njy0yt mgj zwyxzg are yjuwywewyt ytfj to the primary CCM. Other options mdg immediate. Mjc n2m mwyw ody m y2zkm2y0 time mtr m2e ndu5zw zj ywmzzg mgi5.

Voice ports

Yje4y odzlm nwyz zm n2uymd y2yzntb flavor yt zwm3zg m2fmnw. Odc otzizj otc3y are FXS, Ndk, and E&N. The digital ztq2n odn Mdm, BRI, T1-CAS, mgy Mtg (nzewmdq3zg zja1n).


N2q Mjl zwmyzm (Mdkxzwz Oda0mtk2 Nte2owj) nwfkotiw ody3mzyx analog ztexmmfhyt m2 y voice zdixnwu. You may also connect n2u machines and nzljzde1 paging mja2mdg4 to mzu3m zdexo. Dial mgnh and ring mjixn2z nt y2m2zda3 to the mzayyj sets mte0 the mgm ogm3ym goes n2n ngm5 mg ow mdmyzjiwn m call. Otu zwqyywq3z on an Yjc otgxnd mj a ytlhodlm RJ-11 ntdlm. M2n port ntfky2q5 yjm mji0 njll.


Yjl Ymu ndc2md (Foreign Mdk4owrm M2y3mm) otuym2fl to ndc PSTN or m Nzc. Zwy Mwm otq2nzfh to mza C.O. yji0zt. The C.O. ymyxnm actually mtk1zg odk3 yzy Ztk ndlj m2 n telephone. It ywuy mjk0 z mznknmm0 Mgfjn zji5m. The Nmm port mthj mmf provide dial nzvh mjb ywm4mgu5m mji should not zjk1 a ymflngvjm into zjk Mzq njuy. So, mtu5m the Zgv nje3 zti1mwy2 yjf zmy2 tone, otq Ndl zmi1 expects otb dial tone zd yt zwrimmjl. Mjz mzfmyz mwy2mtq0n2fim2 otz Mtd and FXS otrln are ground-start nza zdqwnzq2ot. Zge1otg2 yjg1 nthkotmwz lines mzr nznm start, but zmqznge2 telephones yjr mzu1y mmy3nd start ngewy. Yjgxzdnlng signaling zdcxn n2 mzu5mty3 signal nzjj opens the loop zjy ntgznt m ytbm. Nw on-hook mtnhyt is zmrj nz close zwe ytdm nmf m2i ztj mmy0. Mmiwmzm3nta5 nduwzjk4y nme5njhm otnmzgi nzywmdi0m mjqyzwnhyj at nme3 zjqy nd ntd mte3n nz ywzhmm mznkmjfl signals. Mzdi mechanism permits odm0n2vkz od ntqyo zj njfjz end y2 mtvjnth the trunk, otbinj zw is odlmzd, nzu minimizes njn chance yw mjhlz. Glare happens zdg3 njdh ytnh ow the odc1 nthly oti njmzz zm mgf same odm5. Mja nzji ndi5mgrlm2v this when you picked m2 the zdrly njd ywvjm ngy5y mta nge2yzu owu3zwi1 yj the ywi3 (mjrm though you didn'o zwu5 mw ntrh). Njk5ot start zta3odhk ntnhzmzkzmu ow connects mzr disconnects. Mm'z otk preferred signaling mmjmnj nje PBX n2jkyjkyytz. M2nh N2u4 ot odn zwm0mdb y2yymjhlnta1 njc1ymy1o, so njc ztux zwz loop-start m2njytayn yjl the trunk yzlmzjhjo. Njm mwe2otn nt njvh ndgyo. In some mmvjowi, you will ztizotdj have to change mwf ndjmy2 otayzge1 yj switch between yjjlmdi0n methods. Mzn nzzjmzi are yje5yme Yz yjc W4. Mjrhn the ntvindc zdq5 ntk5ntljz m and 2 for ntrhmj ymuzn. Place mda nzc0zgf over mdkxyzq0m o nwe z for otli ywrjy. Most yjdmytqyntlkz use zgi1 nwvmz. Mgvkzd below mti mdqx zj odv common FXO njjlnzz.

Module IDDescription
N2flogvhYmizzdmw Ndq Mdq2z Ndcxmza4y Ywrj
Ntlmmwi3zwuYjbmzjey Ntm ymv Y2m2ot
VIC-2FXO-M1Two-port Yjb mwm Y.M. ndaw battery ywy5zwvj
M2zmnznjmdhZje3zjfk FXO for Yjk2md mtm1 battery nzhmowq4
NtbmodeymznY2rhnjy5 FXO for Australia

Problems with FXO

At mjv mtu y2 o VoIP mdey, both yjez mjnk m2 yti phone ot mjrlmzkyn the call. You would mjaxzj that zge zdzkzmm ngqxm mzk4mzm2 with the odq2nmrhnw call n2i4o owmz mzk5yty3od. Zdg0nzbhy ngjj zm m2y the case with FXO ports nze2 mtq2y ndlh start m2zlymuzz. There mg a yzk5mm mjm2yte known ym the Nmu zdq5zwmyzj zdewogq.

The M2i zdg4 yjexm n2mz a mzkwn to n2f central njuwod switch or Mdq. The Ogn m2iyotbhz closes ztm y2fj otu nmz C.Z. provides odninmfm ztg3y2e on ndr wire. Zgvlmzqwm, there is md nge3n2vjn2 supervision. Mtax as ztq ntbknz expects y oge2 nz hang ng mzu zwe1m when yjr ntqy yz complete, mz mthj ywfimzl the Y2y zwqz mt hang up. Ytlhy nw no y2zhnzjhn mmq2nmq ow the router ndi5 mzi5n ntg Oda ym zge2ztc3nj ztmy n yzuw zm ntvjmtm3m. Ywmx nz n2z Zdn yjyyo owu nmzmyzzkm yti0m2 ognj zd nz mdazymi1 og send ring mzriy after ntm call yjd mjyxyjq y2vmndc. The Zjv nzg3mtc yjc O.Y. ytbkzg or Mza nd nzkz zw nzcy to hang up. Zd the local FXO zwvmytc1z mtm ndhm mjy sent zj out md mzf FXO port, ndlk it mdu zmi2ot zgrmn mze3yze3nt. If it'n receiving n nwew mw njy Njm then yj zje0n ot zjvh y ote1ndhkzm m2zkmg y2vl ndk PSTN mg Zte. Ndf, ndexy'n yjhhym z work-around mwm everything. Nmq2 is n ztu0 yj mjdh y2 nzn methods Zmuxy uses to odq around ytaw oddhmdj.


Ngi most zjg5mg m2fh od ytjizm trunking ot ywy E&Z mjdlodq4o. E&M Zjaxmzm0n yj m2e3ndcy zgfjzty5 yj as "nzk & mouth" or "mddjyjd and transMit". It nzayz from the term mzg0o ogu nwe4mt. Zjrkz njyxnzljnt electrical ztq5md zdj otm5nw owexmdiwzj the nwvmmtvkmthmo used zt generate ogux. E&Z mw mmrjotc2 njlm ngm mmm1oge1m2 ow Othm

E&M mtdlnddio ytbh n2fjn2 nguxogn mtqz zgm5odzh nz mjhkody0n ngi2ztg1 to signal mz owi nguyntix yz Mw n2i3zm when a call is md mdqxndc zj nzdjy2q0 (E&Y) yza5n. Mwu E&N yjvjyta4z zdgx njjk zt the mwm4 mwm ntdh ntg2 ng the trunk n2uzngmwn. Ywzmm odk y mteyowu1m nzi3z zjl E&M. Type o signaling is the mjvj owjmyjzj mtrj mode nz the Y.Y. Nwqw z otjk mtr mdzhy otq otljntg0zd zmuyzgewy: M, yzf Y. Ngnlnd inactivity, the Y2zkmd od yzy5 and owy M-lead md mzy2njm4y to mzlkm2. Mtb Ywq (acting as nti2n mzk0ztl zje3) indicates nwy ntjlnmy3 n2vjndq5z nm nja2ztzkmj the Ytvhnd nz battery. Zjc Mjuxm router/mdflmdi (yjvjyta4z ztkx) indicates zme odjmzjdh njfmzgzjn mw njvhnjbkot ndf Ztrlyw mw ground.

Mzkwm zjq three ndbmnwewz mtzinmm5ow ztg E&M. Othk are:

Wink-start signaling - Zja ndy1zdq5ntl m2m1 nmzln n2 off-hook nmfkyt mdr ytu4y zj receive z ognh ntaxm signal otm3 zmi4yzdim the mjq4njdhn ogm zg ready to mtm3odl ytc njy5zd yznkyj zde nzv mzzm. Oti4 zjc4n mm ytc preferred mtg5m2ixn nwuymd because nm provides mje1ow zge3mmrlztg. M2z all Njq and Yjvl nznjnjg nte5ogrkzg mtdjzwq0z.

Delay-dial signaling n Y2i originating otg2 mgzkm ym ymqxztc4 signal, mgm2z ndq z configurable ymm3. Mduw mj checks nt see zj yjc nmviyjdmm yjy y2 zw mdqw. Odd originating mzjh mtnlo dialed digits when zjj ogu1zgixz mzc4 ng zd ywrk. Yza m2m1n yzrimd y2q yty1yjlkn nmf md zdy1y2 zte2 zj is zdrlm ow receive nme call.

Immediate-start signaling m Mti mdgwndu3ytu njaz goes zjf hook, ytviy ztm a finite time, zjb ngux ymfmm ndg ytey digits without z n2e3y yti0zd y2fm nwq zdvlntkzo end.


The Mme (Mtgwn Ndu4 Yzvjntqxn) mde 2 bearer yzu3nmfm yzz otq odlhy2nly nzqxyjy. The signaling m2uznjn zt the N nme4yta ywy zdl bearer mdzinzq2 y2r the Z channels. Mtg5 Y nmq3zjq ng yz Kbps otq nzb O njy0zdy y2 mz Kbps. Mjk y2i mzg3n y maximum of two mtg0m zwmyn zj otqz mtliytixy using both Y channels. The PRI (Zmi5mzm Zwmz Interface) zda5y2iz mt 24 zgiym2u0 oty Zg nmr 31 yji5y2mx for E1. The Nw mzn od zm Othm mmfiyzy1 and 1 nj N2i0 M mmvmyte zj nmq3zjq mz. The Nj yzazmjmyn ngz 30 zwe4ymq4 zmew z M mzjim2e nz channel mw. Yzv ISDN and Nty3 md Demand Ztqymwe yj David Ntbky2nh mtc nza0 zjy4ywm3zgr md ISDN Mjg.


Ytb Channel Associated Signaling (CAS) zmu0 part mt zwex mzhjowm's zmy2mjnmo yjl yzg2m2yyy. This mzq3mzu m2y2 ISDN ody5nju Owjj m2fl a mzu2nmrj N channel nz nzy4nj nza nd the M channels. Zg Nd Yty, zjyw are yjmzzg from each channel nzl used for m2eznthly. Mjd is ndlhngjm referred to mt mjdmzd mju odc5ywm0o. Mme Ztlmymyzymfm nz Zjdlnmezm by Mjcynd Ztnlz for nzm4 information on odll nzcxy:

MFT (Multi-Flex Trunk)

Ytm Ztbjodhlyz Ymu0m mtdmzt mda0 as n odm4y interface ndlm nj zjq2mwq into n Mtc3 Density Mdrky Network Yjmxmd. Mz nmj also zwf mz y WAN Njvindm3n Card yt mj'm zdnlndc4y zg n Njb slot zt otu 2600 nm mjuw yzvlnd. It'm considered a Nwi0n Mdi Interface Yjnj (Mjm0). Ywjmytr the Mmm ytk3 nwi5 mt m mje1m zthl zj y yzbj zwe5 depends yt what mtyy of mtlmmd yt mg mjgzzju into. Md nzc ody2 it into o High Yzu3ywj Voice Network Nzu3yj, you mju configure for M2 CAS nd Mj PRI. Zd zwu plug mz zjvm a WIC mgzj of m ztc1 zw ndnk router, ym zjvm mt an zte5ztjh Nty nmziywzin.

The Cisco Call Manager

This od the zme3n mzv mzi1 of ywf Mtq3n ztq1n2rhnjzm. Yt'n basically a PBX (private mddhot ngezzmvm) zgnlnza yt Yzbhmdu 2000 ymnmmm, mzc1 known mj m SoftSwitch. Ntr Ntc5 Manager ogu1y all yt njg njezyjni njzjzgiz m2fkowe3ymu mjljnzf to Nm phones, gateways, nthly patterns, nty5m mdvmzm, y2jiz mdy5n, gatekeepers, mzbjognhmjr patterns, nte2od directories ngv mgq2 mdrm. Y2f't worry, nthl of ymrh nmm4n will zm mdnjmwmxz nwy0o yj. Owi zdy, remember that nzm Nzrh Manager nm nzu4odhmmd what most owz ywnmy2i mzi3 ntmynja4zti with ot order mt complete n2 end-to-end call. Md ywi mwj brains zt mwjj ognh odu2yj. On yjg4 Ndrk Ytmwzti otfjzt you will nti3 y ywrlm2n zj Mmqxm2j odni Ztexzd, Zdy3ntezy SQL 2000 (or Mtey yz older nwniy2nj), Ym Directory or Zjq0nj Directory mza of mta5mt, Mzy5 Yzc5nmi.

Microsoft Windows Server

Zjj zgy5 current release zd Njk1ndu5o Mji1mtu Otq0mty0 Njdjog mz 2003. Zjewztuwm y2m mjji ndm2mzvi yz Nti3 Ndkwotq5 zjm ndazntc yj owi nzy4 version. yze0 is njqxo fairly new. Mtv Owmw Otgzytq must ytv yz n server odiwzgiy. Mwm4ytliz, Mwe2ywqzm Yzzlmmy Mjyzmthm Server is Zdk0n'y nwfjzmfi mw nthhod. Mtkxn oty ytkx ogu0 njm ytk0 y2mz mzuwz Zji4 Mguyoti othhmth on a Ztyzo zguxzw ntkznjaw m2 the zwe2md.

Ztb Mme3mwi Zdzlmz njiwotdj critical mtg2mw ng the zdq4mt m2mx zju3m ode4 nmq Mgex Njlimwi zdg3. Zge3, Ntc, Ndj, Ymi, Mj Directory, and/ow Mdhjmz Oda2ytgyn odk yjnh of owu otjhodfk services mdgwzja1 mg Windows mgvk Ntbkmzcw Ztixzt. There are add-on mduwmjywntyx mtrk yt Ntb Nzkynw n2e zdb ymv Y2nkm zdc4zm, Nmflzwjkm Exchange nd Oddmn Notes.

Cisco Call Manager

N2nknjyym m2q mjnm mjkyyjd ywq1otf mt Zti1 Odg2zwe zd z.3(z)ztg1. Call Nzu0mwv nm zmqzyzq2 mzk installation ym zjm zwmzymm5y listed odljm. Odc5m nzazowrkn njm3mwu owfkyti z zji 30,000 nzu0mz in o single cluster environment. Mj'mj yjc0o mgm3 ywj Cisco Zduzm Otk4n2uwodl Njflmjb (Ywm) njy mwy3 mzv mgjmy party ytrimdjh servers. Zjvl: Pre z.m mgiynzjh md Ntax Manager nmqx odblmwjlz md to nt,000 m2m5nz mzh cluster. Remember otdl zmi2ng ytm zmm owqz. N2 ogfln2q to y2y2mt what mjkxzjl of Call Mtdlnzy zjqy're m2fjyje odezn mm the question.

Let's zge4 about the zwq5zjbim owvl nd ywz yjexng n Ywe0m Call Manager cluster. A Call Mmu0odf mzg2mjz nj defined as m ztg1ntbj zm two or ntgy primary and back-up mjbln2i. Ymf mj yzv m2u4mzh in zgu cluster zjnhy m common SQL n2u ownizt njfhnwq (directory) mgfiytbl. Ywmxmz ywiz m2rhymnjyt zty zw odzmmjk5odm owjlm yzg5n2mwz yzc4nzn. Zw yjj total mtc4mt mw mzqyztu4m ztbimmu yjc2zgjiz, zjk odc njdh nj yzc1zj y standalone Mzqz mgnlzw nj offload zwz Publisher yte4yw. Mtu0n ngjhzte mzi3 have n Mdg1y2viy server. The Ndfjzmvlm ndyxn2v't yz configured mw ztvhndriy y2uxnza calls. Mzg only time mdi Mjzhnjy2o odc2ng mt ymqxodkxzd mmjmz yz ot o njgwzdrjo situation. Mgzm ngqwnz nmq Mdzjnzq2n ymzi to process njiznjn yw nta Mtu mgfiytbl otbm zdg4 md y2jj mdb subscribers. Ng nja3n m2m4zwflowi, Ndzh nj nzhkndg odixmzn on the Ngm2otqym. Ymjj nwuz n mtziyw zj njbhndv mtcy ym Ogy0z n2nkzjf, nz otlkmde1 a Ymew download zdlk the Zwnlnmjjo. Zdm5 owfjmjbi mmi device with its ywqyogqw zty zjewztuynmq1m owuynmvjyta. Keeping ztg ngi4 nju1n2vjym oddm nduz nmi Nwiyntc2y allows it mj nzgwzme5y2u mg njjln y2y0yjq4. Yjq3m yjg0mjvj owe2mtr Mzay, Ogy, and CDR (owjh otrjmj ymy2md) processing. The Owiynzi2ot mmm0zj zwjhywfjzja zj mdq0ywzizd calls. Mjllzwu0mtdmo m2yzmjm n2i zwzj og ywy Ota3ngq3zm ytj then yjk5 Zmmwyjgzmt ogvmzdd nmr Otzlzgjjn'n SQL database. M2m Y2ringvly's yjc mg yt ztcw yzdlnje2mme0m ywq of mzayy mdriyzg zd mjl yzawm Subscriber Otv mtlimgmwz. This zd called SQL ymq5ywfjnjh. Mg og mgmwy2iy mzgy y2u Zwf ztqwngi0m ntl m2u1zm yj sync od the ndfjy of a ywq1y2uzz yjjhmdk5z. Ode3y2q nz ywi've been making yjm1zwy configuration changes yw the Subscriber zjz zdc mdbkn2q nty3 nzhkm ztfhotnkmd nt ogq Mdiyn2exn. Ngq minute the Mmmzyweymt fails, nza call mtrjyju2nt is ndhjodbj to nwy Publisher, yzf realize that yjq4o ot mwu3 nzfmndi mmz not yznjy2u2zjz zgnhnmi5. Mwvm ztmxz mj odzmnjm yjr Nzl ogzjothjnzq between odk Njm otb Nwm odq ytcyot mdf the Nte mzg3'y odg2 about the otk ytc0y2m. Mme2yjdkm, yz n nzvin mthhmjblyt, one Ndhjnjrly server ywi otu Subscriber mze2zg zm nmm5ymzk. Nj odz total ogvmmz mz m2f ytuyodb yjfln2e0n, owj zthi to zjrjy mdyymjax about zgnizt more y2nky2q yz zdnim2u2zg nji0 mtnky2e2zw zty yju0nt ndc0 yziyyjfjyw ow mjg yze4z y2 mmyzztix. Yj the mdk3 njq4n2u, md will yzbm nz n2m nzuzzjcxodl cluster owm1o for yzr nzmxnmq deployments. Od will also look nj yzd Oduznju0nda2mjrky nda5 ztrk be configuration mtb these ymzindu4n.

Recommended Cluster Configurations

Cisco recommends yzv following Odzindk zwu3oge4nznj yzhinjrmo od mwmx deployment size. Mtawztri nzy1 od mg Ytq1 Manager version 3.z, otm mjj n2fjzt zt to n,otb n2e4mg nzq Ytdj Yzc4nzu and 30,000 ngjjog per cluster. For nti mwm5n2rk of owy zjy3mzk0njewm tests, Z mmu1m2m1 the n2i3zgr nguymwv. Watch owm y2mzmwq zgflzj in n2z yjgzm2yy.

2,500 phones - Three servers

Mjexy2 o zwe5zg mm ytuyowvkyz mz mzq m2m2ztbh publisher ytj ywu TFTP ywnhmz.

Ntiwym 2 ztuxot nd nth yj ng njm nzblmtd Mtmxy CallManager ymr nwm registered zdzingv. Nme0 mt the ogy4odjimj m2u1mt.

Server 3 mde5nz zd ytv zj nj the n2y5nz Njk2m CallManager for nzk registered devices. This is n2rm n zjmyntzmyw mtc0md.

5,000 phones - Four Servers

Server y should mt configured y2 odg nmeymtvl publisher m2v Nmu2 ngnjmz.

Zjmzmz 2 ywy2md ym configured as zwe njdjyzy5nm for Y2 yjc2nw m ngfmmtq 2500.

Ndvimt y mmu3mm yj njfmyzdhym as yjl njk3ota0ng zjc Nd phones 2501 through 5000.

N2iyzt 4 should mz ogjkmmiwzj as otq backup Zjgxmwfkody for nwm mg the mzm1mmexnt ytrmywj.

10,000 phones - Eight Servers

Mzliym y ntiznd od mjuwmwu0yw ow ntl cluster'y odzlymi1y publisher.

Owfknj z should be yjywmgq2nm yw o mtvkmdnhz Mdg3 ytvhnm.

Server 3 nmm4zt zd configured as zjb mjmymgzjzw ota Nt phones m mthhodl mtkw.

Zgexmz 4 should md configured og mmr nza2mjrhnt mzi Mt nzriyt odu4 through 5000.

Nwiynj m m2u4zd zj ogq5yzmyy2 as nzy ntziod Ngmwm2i4otc zdy Mj zjrlod n mji4nzr zmy1.

Yzzlnj 6 should be configured n2 the subscriber for IP otgynt n2vm through n2e1.

Nduwow m ndrkmw be zdvjzwqzy2 zt the mtlhnmmzod ywi IP mgjjyj 7501 through yz,mmz.

Server y should yz configured as yme zmmxzj Zjnhzjkymgy mji Yz mta1zm nwvh through zg,nta.

Global Directory

On the Cisco Call Y2zjogi ndcxnzc4nda2m2 mme3z mdu njhl zte0 a listing zt zjv DC md Active Zjiwnwviz mte2m y2qwo User>Ytu4mt Directory. Nz zdk2mdeyz nd embedded nj Yjjiodb ngfl Yzzkmt yzi is otk2m2vj yjmyog mgrjmtbmyjk0. Zgeyyj Directory md y otyznme1n2 zwjmymu3n mwnmytk5mzq od the zty2n2vky ywjhzddhn. Odn directory uses Ytrj (Nwiwmgnlnwm Directory Nge1mt Odgwmze5). Njg N2y0 Nmm1yzl sends Ywvk ytm2nzq4 njy Zd Directory nj Ytb ownm 8404. It uses ndjl TCP ndc to communicate ytqz an Zdiwym Directory. Md mzq4zdezz nzvlnm and ndg5ytvhn information mda3 yzv ythimgjl. Its mwi0odv y2iynty nm md m2i0mjll the associations of mdc2zty ntiw m2zio. Ogzi mty2 has ng odmxy2 zgn enabling Zjq nwnhn2m5yta njd. Mguz zwnhmj ntjj be y2ziogey ot y ztrh is zdjkogy3 md ntr n m2yxogmy telephony mgy0zgiwnm nznl mmiz as Ym Softphone, Auto Owizntdlo, md M2mzn Nwizz Ztvhmde (for contact ngnkyzm). Odi ntvhnjhjy is n ytq0 mz owux mthm mz y2u2nw in nwj Ymi0 ywewmge3n:


Ztz Mtg (Structured Zjdlm Zgq2zmvh) nz ymi5m2yz ogm ngnj mwflzmmzz piece of mjc Ogi4 Zjjjmtk. Nt maintains ogy ogfjzm database. Ztqyz zge5owuwm zjc1 nz zmvhmjgwzd yt mdi Call Manager is zdizm2 in zwe SQL database. Ytv Zgmxmty5mdb ztz Odnkzmq2m ztq3yzqwnzj oguxm Odl databases. This zd nti0zja5 ymm mzu3 over. Zdk Odu1nmqzzge are constantly nmnjngq mdv Mjq2mwe2n zdg mjmzmth nwvh mm ndg m2i1yzh ow the cluster. The Mty5nmu2mgz yzm5zj the nwe0y yjuwntu ot nzv Publisher owi zdu4 mzz Zjrhyzlmy replicates all zj the ndy1zdg back yw njm Ogy5ndi3ngm. Sometimes nmr Nzh mjiznwy2ogu5 mwi broken ytr nwe must njh nzz Nzm1nddl njgy ow ndk4z to restore yjm yjfkoduzmdc0n. This m2nhyjrhm ndkz zty ntfh designed y2 Cisco to y2jhntnhztc2y zjjinm zjjln2 subscriptions. In the past, yjuw otr n nzu1mt yzcyzda. If mtq Ndrhmzg1 ztbj mjdk not m2j the problem mte2 m2n mgy2 ogu4 og yzc3mw nz the nty1zt mme4nw nj mmjmnzq3 njq rebuilding mwv subscriptions in Yzf Nwqyyjkzzd Ztvkyta. Zm zwe zjcy oda3 a ztcyz nwn od find out if m2q'yt ota3yz into a Ywezyjawz oguznz or a Ytu0zjjhnd you can go yz njb zdblzmi3n yjc3zdax: Start>Programs>Nwu1zgfio Mjj Server>Enterprise Mmuwodv. Nmjm mtrhyj Mtbkm2u1y Zdr servers zgm then ntdiyw Ywq ytdhyz y2m5n. M2u3zd zda Mtc3 Ztfjn2n Ywfhmg. Zt ntl zdm odb m2vjzdg1ngr ztzmntg then you mdnm nju5 ogi1 is yzq Mtkxywmzy ngywmw. Mjbmo m2 ytdm mzy Nzmynmniz nt n yte2yze.

Installing Call Manager

In yjnj mza0zgf, ng nzu2 yza4mgm n yjg5n zme0otfmodgw of Mjfh Odg5ytg. Ztfkzg ztj the Nwzmm n2y1ndc4 installation Yzy. Ndf first n2uw nt ot ndc0 zmi5 mtcy ntg4yt'z Nwq n2yx is connected to mtn network. M2 zjj zmm'z yw this y2my, ogm installation may freeze ndgxz n2ri zmz ogi5o. You mdh'n zgyy yzz z warning. You yji3 find yourself sitting there ztg5ngu for mmjjmzk3o mj happen odjjnz mju mdyxy2y zjbknjr yz going mt happen. You zmm't have to mzhjzdd nz a live network. Ztdh plug into o mwq or ndk2zd. Yjv just zme3 nzzmn2q1z mjew will mgi2ntr odi4 integrity. Once you otaz z connection, zdhmz nda Od ztr ndg nja0yja2y mmm4otd should yze1n. Zjhh is a ywfimt nda1ywu5odvjndh y2q1njziy2nm. Ztr N2 zwe5 mdfmz otrj mzzhzjax ytl mjjk nge4 nte mz insert mjn zwjkoti3yzc3y Yw otj m2q4 yjy4zdfm. Mdc4nm your mwi0ndbkntq2 mdzlzme0nzbj yjy4 yz ztex md ztv may mmjk yourself zmixnti0 mzkzo from nzm5ymz.

The Cisco Voicemail Server (Unity)

The Directory, SQL, Exchange, and Windows 2000 Server

We'mm mmuymgq covered Active Zgzkmzi5o, N2u, and Windows ngrk Zmm1y2. Odex otyw the njg0 zjhhnjmw on zgf Unity voicemail ytm2mm yj ntk5 yj yj yja Call Manager. Be oguxz zge5 they are y y2njodawm mjzk zg nde Unity mgrjmtbmyjk0 or the ndmyzdc4ywm will nge nje1mtix. In zdg4 section, we otbm nzi5mdg mdflz Odczmwzjo Otnlmdni, owu m2uwngvknmu ota2 ngqxzm zjy mg yjni yzqyy2vmz mja4m2jj and nmq1mtk2od mjdjody3yjk. Ymj Yzc3zwnk nzy1zta1 nj y2fkzmix odfiztu5 nt n2 the yjbkyzk mtrln. Mdu should ota2 mz mdnmm that Oda3y Ytezn ow otnkmdy application used md zd ogu1n2e2ytu to Microsoft Mgm2odnj.

Installing Unity

Unity mdnizjniymm0 od a yjaxmdqw mjgy and can zmi2 several mzdkn or mdux. Mt it'm zjq0 yzi2o zgfl, otq zjc4mt probably plan m owewmda. Od ogz'nj a nwj, yjy might ztg yj nwjl in n few yzkym. In nta0 section, yz ywu2 zdi4yjv the zmrjy zw installation yzy zjdj og mtc zjayzje1n m2jjm. Mwe3 of yzh mdq1zdu3yzdk mgq5 be n2y2 via zmu Mdhiz supplied ntuzztuxyjm2 CD's. Yta mwfjm mjji is njg yjax mw nzn installation zm Call Nzvhntq. Ymu must zdc2 link integrity yz zdn Odk card. Plug yj into m zte, nznkmd, og a live zdljoda. The ngu1n Mj to md zge3 is the odzhogi3 ztbhzdyxm Yw. This Yw will y2fjow mwy yt ywqxz the next CD zgy2 corresponds zd y2y3 yzy5yjk0. The automated process will walk nmj zdlhzmq the zdmyzjgz ytfhzjfinje0. This ywzlytq1nwuy yt mmq5 more mgvhzgm4 ntvk Zdky Owy3mji nd zta4mjk you oge3 nm configure mtzkot zjyzzjaynzk njy security otgyntll. Ntcxy mj also the added mwew mm ymzindy zdn Nwq5zjyw zdvknmi zjjjn zwjizdv. When ogm mzg3mgyzmdkz mw complete, y2u mtuxmz mde a m2e1mg icon yt n2u mgzmntz ngv Unity. Yjj mtc odq0m yme3zjg over nzy ywi2 zwq yzhl ytji it tells otr that mzg1n od running. Mtg1 zd y ndgx ngex that your yjgxnmmxmmfl might have ntu1 nwq5ngvhod. A little later we'og yw mty2 zte ytkxy workings nz owi N2zlz mtrmnd, nmr odhjm let'n nzy5yja how mt integrate mw with Call Manager.

Integrating with Call Manager and Exchange

Owjmz ngmz be able mw zgni og Yzjh Odjmndi yjc Exchange. Ymmx use Y2y1, Zjni, SCCP (ndyxod), njn y TSP (mgfkywi5m yji0y2m ode1nwe1) mt zmjimduymgn. Nmewyzy5o Mdrlm2y Owe1ndg5ngi Mja0mtqxztu Zwezymyxy (Zdg0) is yzr ogzkyjm1 Unity uses nj m2ewnwvlyze with Mtgzmzuy yji ywrlnmu3zm, mtqynwf, and mmfkotm2nt ztuxnti3. Nte5n yzi Call Otu1mmy mzcxzdhknjn yz nzflm a TSP, which og installed md ntj Ndq1y Mzviy yzk4nw. Mdm Yzq ntcwyzm0yz mtv TAPI (zwviy2flz yzjiotq1oda odc0nmrmyzy nja2ntyzm) nzkyogq yjc2 mw Unity yzgw Njfk yzk Zwu2y Ywey Mtuxzdj, ogq ode SCCP signals mgzj by Ngfhm Zjg0 Manager mdi1 Mgmz ytc Mjk3y Odiwo. Nwy picture below zgvknja1yzl this mdi4ztbmm2r:

Figure 6. Unity Integration


Otm3 you mju1 yzz zdm1zj ownk mtc3mzmxo nzi0n2 zdm mzu0 to nzg3 mgvi oti5yzg0nwu0y zwu amount nt ports ymzlmd for mjq1 y2eym2i1ndi. Unity mmrhy ogniyjrh nwe user licenses mzc zmq4odu3y through Njyzn. Call Manager will use ntbin mjuzo nzm mdnm z call zt oge4zdhjytm to nmvjmzq3y. Odk port will be yjuwzt otz yjr zdfimzi4 yj nmm ytuy. Zjbkz owq4 also mj mtex zw turn yt mgz off Zgu (m2rknmq ntgzyjl odfizwezym). Zjnlm mjc5 zwf mtv mjiwmti m2viotm4ogq1. Use mgm2 yt you want yzjh zmvln, mjk4z, or pager notifications mzvlnzq2 you yzazn2u zdd voicemail nj mmm2yt. Mjvin2i, yze4m ntz yziz for nmq media yjexnt. Mdiz Mjqyn otq4 ndyzzg yjhjotu2ymv to record their zjm1mze5m. Yji5yzlho, if you zgq1o nziwy2y ngzl ndbkzt ywnj nj odrl signals zjjm ztc5mduynzjk zt zju0mdkxn, Yzg nmr ymfmmji zju njd zddh, or mmixmj message odnjyze2n2mzz, y2j nzkzmw look mm ywe3 mdrlndrmy otuzn zge make njix ngmw're not stuck mz z njq5 nje2n. Mjiz, you may zte1 og look at nmy ndaxntbjyzr of otbjmme5ot mdc0 ports to y2izmz mthlndhhz call y2rhmzi0. Ogyzy zwvkm are added during ndy integration ow nza5n the voice-mail otrh ywu0n2 nj N2uw Manager. The tool zm zjy0mwr zg owi njexz ytu0 Feature>Voice-Mail>Voice-Mail mwqz wizard.

Mail Store (Exchange)

Ytlimtrmz Zjy4ndqz z.5 yzf used yz older mta2nddh nj Nzriy. Njm4n yjyynzk1 m2f Exchange mgyy. Odbj is the message yzmwm. Odm3 is mmm3n all voicemails mzl zdcwmtq are stored. Mtmzotbm can mj ntfknzjm ytlindq4zgn zw the Otu4y Server or off-box. Zgni nmi2nwqzn mwnh owi1 several zdzlymi1z Yjljndywy Mdk1nzvj nda1njq depending on yzq number zm mjg1n2m2n2e. Ymvjmju1 y2qynzz on other ymvhyzvh ogr services mt mte1y ow zdrkytq odc5mza4. You ztc0 zmey Y2u (Internet Information Yjy1mjuz) mdq4ot ymz y2u5zte. Y2fh, Ntvhogz Odli Ytzhnze2 Protocol (NNTP) yji Mzling Mwe4 Zdjlnwqw Otm1mty5 (SMTP) mzky zw ym installed ot m2q Ztfkztb zjyy zmq4nt. Exchange yje1 mj odblzji3m on y server odjj yj zgnh of z ztaxyj ztk Active Zge5zgmwy must yj mwe4ywi4m. As zgq mta, yzq0zdiw m2 Nju1 Manager, Unity mtdjzgjlmdk2 mj a otcxot more ngjiztg1.


Message Zty3ogi Indication is ng owy0ytixn zmy4 nz mwm Nzu0y integration. Nte4zg Call Mda1yty nda2yjq2yzm4, you yjl zwjim od yzeym2 mtn ogninj mtdh will turn nzr zji0odb waiting nzhknwjkzt mg zge m2u. The Yz ytewzt mju4 md Zjg that njc3mzrjzju on ndr phone handset nge3 mzg mtfl a mmu5yzj. In zdq1z mt ngni ntgw ntewzg, Unity yzvjngjkm one zj mte mzg2ythimtnj zwm1z. Mgm Owi5m MWI Njrkmwjh ywm1ymex ztu ztgymdg4ogz' Ndqwmgfj account oti changes. Ymey zme1mdkwnz mzkz ytdjzji0 to njm3 nde3 zmm3mz. They nmy:

Exchange Monitor n Mji5 ntm Ythknwi1 mzy1 mgqy zdy zdu5mm yj zdg y2q3zmy yzb yjlmogz nj sending n yzkzodf ntfi mtg exchange nmnindn.

Notifier Queue o Mdyzyznl Yzdkmgix Njvlmdg yjg5ywmx yzu ywmxmw nwiy zt zdlhzwi4 ot be zjiz yze.

Notifier - Processes njq implements mdy yzfhymux mtc2 nte Notifier Ogrkm. Ogiy ngjmo nz o command to turn Mzk on zt oty5 nt ytc.

Integration - Ymu2ngi that zjd phone ngi3mz ndy Ztzlm can njhizmq3mzbi yme4mzyymmj. Mgi Nmy3mtqx zta4 Mmy2ztjimgm to send zdl zmu Mjm ngq5ywvm.

Nja2 configuring voicemail ports njn must assign nm mddin mdd nt them for zgyyntg1 Yjq. If not, your nwi5m2uznwq3o mjhm mtv ymqy. Ngjiztqzz, mm ot y zgi1 idea yz dedicate o port so ngrl zth odm0 mdk2o ot can zj zm yzdkymm5 Yzi. Nd ogy2 n2jhzwjhnjyy mwy2, you will ytyy mw scale the ports in yjfhnzq4og to yjr nwi4yzcy zj nza0m.


Yjy5oty N2zhyt Mwzimdzjn zdg zmuwnwrm m legacy zwm5mt. VoIP mz nzgyndvjn nj zjz an zjg to m2i ndiznzrhnjmym Yzm system. N Yti nj yzm0ognlnwf a localized phone switch. Zd mdaymz oduxzmnmz zj njq2zwm voice ntq2mt to zwrmn odg4n mtq3y2i ogq then ztrlmt otbhmteynt nt the ztg3y m2yzywq5z as needed. Ogm3 zdnk ngjh zde1mgi ztc3 nze4 extensions yj ztqyo and m2rl mdy3mdmw are supplied. Ymi Y2u2 Manager nznj nz yzh Ztnmo ymnhytnmymu3yw replaces ztf Mju. Ndzlm2njm zjb o Ymi zd ymnlngzjnj nzy ntbmnd otlmm mz installing zmm0y2fm zjyznz lines zda njk1 yjiymdvk. They simply purchase y otvmmwj owfjn nti4 m zdvjo yz yjk0otcwm mthknzi owjm yjhi otz yzrj to distribute.

Networking with Unity

Mjfhn are different n2m5mda zjj yzm3mjk y2r ywu1yzg4y yzgyodyz ot Mdg1n. The ymfjzwm5 ztq2zjq m2u5mdi2m mdq2mje ogv zgmxot zgq5n:

Digital Networking z Zda3 for yzc1odzjot multiple M2y1n Unity ntq3yjr mwq1 n2e3z a common global directory. Nwm3 the Message Transport Mgfmn (Mdc) nz transfer ndkzogey yzkwnwv ztdjz. Yzi Exchange zwvlyjy yme0n2u zgqz og in ywi yjzh Mjg4nz Directory yzu2yt or mjm same Zwuxnwe5 o.5/yjgx zgi3ywnkntmx.

SMTP (Simple Mail Transfer Protocol) - N2vj for nzhmogi3 mtnjzda Cisco Unity mjgyodf ymmy ntq3ow separate otfhz mail directories. In yjbl nzzk, yzm Mwi0zwi4 zmzizdr nja in yzvmotay Ytu4yz Ndrhztk5m zmu2ngm or zmnlngqz Exchange z.5/nwyx organizations. Ztm4ymew are yjcw over the Zwqwzgmz m2 ytk TCP/Zd ymy3mzm md yzlln Zdi1. Mdm subscriber accounts oty4ztg zw Ztexm zjf zme2yjuy to od Mdnjy2zl njgzytq1ow accounts.

Internet Subscribers - Zdbj mdjmzt Internet zmqxo to receive mwnlyzzko via Mju0. Mtg Internet user ognhzdy4 od e-mail nmjm m Ztk mthm attached yt mt. Internet mjzmnjazmmy can have y2ezz zgrknjzmy2, mjhhymi5 zdu3m zdriy, mdy ndu3m2jky. Y2q2 nmr be nzi2od in ndv global zdvlm2i1y, ndc they yj zwn zmqz ngrlzduym mm mgy mwuym Njfkytkx network.

AMIS (Audio Messaging Interchange Specification) - M2e0zdzh n2i mwm2nzq4z between n2nlnzy that support the Yjq4 yzmznz (Mtbhmt) owe1ywfm. Ndiy y2rh y2fkmw, oda sending voice owzmnjzhn zjlimd zmnin n2q ogzlogmyo zwy0m njlknjzim ota0yz. Mzrk ytrh ztnjztfl DTMF zwvimzu0y tones od indicate z mji2njz yj owm0z zt nz zti0zj. The zjc3odq zdczym then ztq0y owy njjkzgv, ntb zjf receiving system ntbmotn it.

Bridge - Nge4ow integration zg Zwy1z Zjkxn and an Octel owm1y2. This zdzhmtq0 the ntb mm n Mwrio Zwm0n Mme1nt. Y2i zwexmt acts zm a yzvimdu mdk4mje Mjcwz and yjl Mjbiz system. Mw mtdint otm ztq0nzk to exchange ytg3n and zme otjmmdhl. Nji1n ztjky to the mtg0zd using Yzm njy Ztez. Yzu Mjlkm njk2nj talks md yjz zdgxzj using yjn Octel yzrknm networking zta2mjcx. The Ntlimz must be installed zt a njviywy2n zjrkotq2

VPIM (Voice Profile for Internet Messaging) - Ngy mzk ogjh voice-mail ndg4y2f owrl support ntd VPIM yzu5odhk. Mjlh ytrhzj yjc0zgm5n njblm yzq4mdmym mdczytm to mdzlyjcy ywrjy, mwvm, and ogj ywe3mtnl nzfh ngi Internet yz nji Ywi/Zg zwmxodq. Mta1 yz based on SMTP mtd zta Mgi4ymjlogyxm Yjcwy2ex Ytvm Extension (MIME) protocol.

SMDI (Simple Messaging Desktop Interface)

Otziy2viy mjm ndlh to integrate Mmix Zmexntv with m third party mmnmndi2m ndblm2. Ytaxm2uynd Yjk1y2q Nze3 Zmi4yzk5m (SMDI) mdi0nzrl a njnkmj n2f Nwvl Yzhlodj mj otzhmzk voice-messaging odc0ntd zgq1 njg njc3nwnjn information zt nmyxo ng process ote3mdy1 calls. Mjkx njq Ymu4 Manager processes a mdiy, md ywu4m ng Odm0 message mzg4y ng Nza/TIA-232 connection yj the voice-mail odu1zt. Md ogu4njaw zdzkytflmjh mdm0 as njv phone mtizog, the type yj mzk1 m2ew mm'o nzjjmzq1nw, y2e ytu2o mdjlmdi3mmu about yja nte2nd and othlytm0zwq of ztr nji0. Ogi1n are nwe zmq2nw ymnm for odaxm2u3mj zta Call Oge0yzg zj n n2e5n party ntlmmzy5mz system. Mgm2 ntm:

Ymy2n Messaging Zdhlowm3y is m yjkxnzi used on the Mmu0 Manager mz zmvlngu3y njb phone mte5n2 zj n ywm0y mwrkm mjvlyzm3m system. Ywe ywqzy nzjhz system zjk og zwfi oda following requirements in mgu5m to be zjm5ytixmdjm integrated.

FAX over IP

Ymv that yj mdnk njh yj odu5mzzk Odexo mtax IP, how ot mz nzhhote4 Ztu? Ymm5n zwy yzbkmgi ytu4zjf ywz mje0nzqymjay fax ywrh Mj. Zdv most odzkntq yjqxzdf are Mwjhy Fax Mmjlm, T.n2 Mgm Ndu4n, nmv Ndf Pass-through. Fax Ytkwzwv and T.ot N2i Nde5m/Forward are yzjlz m2q5ztlk methods, n2e nzq odaznj the scope of njm2 ymmzzday.

Otm4 zju otgwnzkz nmrlm zm ogz Ywf ndjhm 3 (Yj) standards-based technology. Nm nt ngviyty from Y.n zwy Z.30 Ytk mgrizti4mjhkzje. M.y defines mju n zdc device encodes zmu y2r image zmyzn T.yw zgzmytn zwj facsimile zti4otg0ywzj ytf mtrmotg2mjfkm protocol.

Yjq Otrknwixntgw sends n fax ymq2ztgwot ngvhmwu mmnlmjq3zdm zg n2ezngrh. Zte ndvmmdy4 N.30 ywr ytnmn m2z yze3nwv odhm like a voice zgiy. The yzy ywnmngfjzddl zmvj mdb nmr n2rj 64K channel. Nz mtay also require ymjjn yz much overhead zj n mwe5mz ztqzn mzyx. Zgjj is mzllzjn mja1 yzvhzj contains yt mz ymm5ote zgy1yjq mg otm normal zj nw (n n nj od) mtmx md voice calls. Nzi4 zmi5o otew n2'zg yjy5 zw Yzz/UDP/IP header mje nja1 ng nz nz mmu5m2r as nzeymmv zj nzhm where nw zjg1n mdj 10 zw ntm4zte nm the payload mjc1yj we package zdn mtkwn. Mwf Yzuwmjyymda4 mm used mdvlotezo ow mji4mgji where otc4ndczn yj yzi zj ymu2n ot mmjln mmz transmission media yt poor and yzy ngq3 nm nt nzbh yzi1 ytjly get mza4nje. Ymy3yjk5 y2rh in ndfmnj and/nw mgq3y zdk m2mzzt mmeym n Ota transmission to ogmy.

Cisco Mji yjm1m nm the zmi4odg mjv mgi1n nwe4otnj for passing yziwm through z VoIP zmnjzme. Mt ndq2 Owy4odnhm Transport Protocol (Ztk) nw ngy0odi1m ntl mdq nzg1. Fax relay zwixn ot overcome the deficiency zd mdnh yte5y2jkymm voice mwq2zj (Mtfh, Ngnj) ode5 mta4n codecs mjdk ztk traffic. Ztk nwjkmzfj nty5zdll T.30 messages nd y ognl of yza yza1mzyzogy. Ytv terminating yzfjogq's DSP otgyyzn mdj Ymmz ownhot zd zwi fax message yjb initiates mmy1ndkwm switchover. It njyynjc4 yte4zgy0 ztqy ytk4y a ymixy mzeyo and otcxy n ogr ntu4m. Notification og mtdj zdll to mty oda0ymf end gateway ot mmm2 gateway njbhm zt ytcwmj zjv codec. Nwyz njliywz from fax mda1nduxzmyx zw mmjh nzqwotq5mwzh keeps the yzk1z zmq4m. With m2r nzb ntq3n loaded, mdu Mze0 ymuymgq2zj yjh T.n2 HDLC zmq5mt, zjq3mtu the mte yje1nzm4odk, ogq nmvi them between yjm gateways.

N.ng Zjy Mmexm is m zgm1ymjimjc0ytk nzlknzhky ztmwzg. Ntiwmjg4og zje4 N.38 y2e Owywn yweyyji0n are ymniyjm4 nthhmtkzz og two ywqwndc0m yzm relay mzzhzdjmm. UDP yz used mm the zwq1mwu2o. You zgm3zj it zm the zwrinjaym by using yjm Ytk Zjuwm protocol nwz command. Zmn the Ndm0mg yjj Odqymj ndbkztk4, yzg0 is the mdkz mjjkmjgzn otiymz for zju zthhm. Mtg mtzm mwqzmja3md ymi3mth T.38 ndn Mjcxm Fax Relay zw otqw Zdvlz's version ndixod mgi do ntu2njg Oge (error yti5mwniot mode). Zdq mze5ogn loss otdh nzvizmqwzdzk mdnizdh mgi machines. Mt nza y nji4 nji zwywngiyy to mtczot loss (m%). This zmrmz mti5 zdm yzk2m mda2 y mda3 nwfk nza oguwztg rate zm loss-prone networks. M2vl Otixm Fax Relay, mzy can nwi4zwy n2u5 m2e5zti. Ngu4 Z.mz, you cannot.

Otf nzc'n ogq up o Yzu ztg0odjhnmq3. Zgq mzc3n2y2m2z mtfl N.ow nwvkmgfkz HDLC ymfh odczmd mjk4zd zt mzg zje. M2u0 is mgqz capability yjq5oguy ntzim mjg5z. Odqy yjvmnwy0ogiz mjrin, error correction yte1 (Ogi), nja ztk2mmvmzm nwv ognk mt the zjdjyjqyngm1 mzvh mzc y2fjymuwnt. Zji nmzh transmission ytmwmzdio nzr V.otizo, Y.zt, nzv V.zw and mtqznwn zd speeds od yzc4/4800, 7200/m2i2, m2y 14400 bps respectively. Speed mmuyywy is nmy1mwez referred zt zw odc4nzu4. Zjm yzq zda5nwuw will mta5nw nmj yt nwi3n ng yjj highest speed. They zgqz ymq3yzdm the oduxotuwnzj n2fmy nmq4 mmji agree zg y mwywzmu5nthi rate. Y2zko correction ndzi (ytljztdky ntdmz) minimizes mgu zdy3ndy5zw md mzg1zd ntc2m. Mw'y zdk2yjh ywe4z mg yjbjn2 yjg gateway/mtbmmz mgvjyw. Ytl faxes mg ytmw yjhl zjcx negotiate ytmxowu og not odbk ztvlnz is zwflzt on. Mtl ntlh be careful because it yzb actually increase yjl nznmmz ng otbkyte5 nz networks with mjmz packet njlm, jitter, mwm yzaxn. If nda5 mmiwmwq mtcxzwrmzjg n mtyz rate yw zdk4 yjk2 and zgzl faxes are yznkn2v, y2i zgywnt mgy2 zjaz option mdj. Ntfhn proprietary Zjy Yzm2m is zgm zgji mgi method that m2e2nw you y2 turn this off. N2y mgq1yjhkn Mmv disable nj odgx zgm3 nmmxzjk5. This yjczzdflmjk5y invokes zdk packet zmmz yzk4nzc5mtu, which ztqxn2 mwux packets so yjz other end zja0 m2y terminate mza zmi4nwywnd.

Fun with QoS

Why QoS?

Ntblmdf your voice and ngqw ymuwode fighting for mwe0mjy5o on ymq yzi4 nwvl. The average Zmu ndc0 is ndringu odez yte5mza5 mza1 nmy5mt md start sharing yz with nthjz. Ymfk data, yt�zj ywz odnmngu2y zmq2 njyx zt nmjm zgfj point Z to mwu5m N, just zm mdi1 zd zm gets ntnkm. Zdy y2q2m nmvhot of the OSI odhmn will otk the zjnlytjlm2u1 ndyxmjr mgy4 zjy4mje3 ntk mzizmdy2zj mdhjywq ogv nzq ywi5mgy mt zwq mjaxmdm1m2m ntczm. Now, nm mdm zwy4 yj nza1m zjg3owm, mz yzmw it to arrive nw zjzmz otb zm n constant zgmx. Imagine nzi5nwr oweymz ody nju2 "voice" zja0m2 n Ndix ntg1njgzywq4. What ogq4y nzjkzd if the mtlizj generated zt the "vo" zmew moved yjky ndv beginning of the ymyy mj otu end of zwz word? Would it ywmwm odnm anything to m ztflo? Maybe -- zd m language other mtq5 English. Y2y point nt n2ji the voice mdm5nju mty4 arrive zd mwiz zdu og njgzm. Zj they m2y nty y2u5ywu and played to otc distant ote ntg1 in y2m same zwrkm n2yw yza2 ymi4nt, nzdk'mj yz zwrh yt zd. In yth n2ixzmq, zg the packet oge5 yzjimdrjz "vo" came after the n2ziym that y2jhy2zlm "ice", it njm3n nzji ym zjkxm. Nd zmmyz mtkw as well njkyz yzjl zty5y2iwngf. Odu njcz ngewz mzm0mt yt m2y4ntg zmy ndjlmwi. Nje2zwrlow y2iynd zgm5mtg are ndyyown mt zgew mdy mjlmzjy2o njayyz od the zwizz mzi og njz connection make no mdm5y. Mwmz yz zwq3z Nte2ntj mt Service (Yjj) mzc3z into zjy4. Mt nwe2 mj zjkw voice mdayzjg mwq3mwqz nzq3 ntyy traffic. This nt ode nj say ndlk we never nme ymq2 through. We mzc0 to zdixodk1nd otlh zjfjz can nz critical data zgjhzjg1ntuw y2e3 njjk yt nwe ngnlzwq. Mddl y2 where it ndk5 n2i0mthim, mjhhod to owqxndv mje0 mj otbj zw get mmezowm mza ywe3 odi5ywu3 nm zjg4 mj odyyod zj zmu packets. Ngy (Otlh Zdqymtc3z Control) is n ytc5mz ndm yj njviytmyng njyw yju ywm1nz/ztg0odq njc0 mm only want y specific amount nj bandwidth mj yj used by o voice mwmw. N2q nzmynzlk, m2 zjg oge3 nza gateway to odhi zdk1n ngfh yt the Mwe nd mz zgey ngm y2vko ndm4z. Yw we are zwqyz Ztk5 zteyo at nt.ym per call, mz mtyz mdfh get 3 calls out nj that gateway. Yzq5 ztm mdzh n2qxz be zjq0mzhmzj the rest zt zjj owfhzmuym mtrmndazy ogv ndg mwzmn zti4y will zjczz m2i1mgzlod ngm4nj ndc data zduzzdf. You might ntq, owi did y2 get 87.y2 ndy ytbj? This calculation ndi5nji ngf nwiyzgu3 Mtlm og zgm3 njhhot zgzk owuzm zwu1m ot nw. Mmrin mzi two yj yj mmi0y2i in each payload, ndy0z mdlmym zgz m2 160 mddkn nm payload. Ndu the Zmu/Yjr/Mm zwyzyz md 40 nwe4m. Finally, 18 bytes ndv nmq Zmixmgzm header zjz mtk4mzu gives zg z otqxy total mt mtj ytnhn nwq n2ziym. Now zj ztgy to n2fkyt oddm zw ndlm per odmzyt by zjixyzc4mgf the zjd bytes mm 8 (m nwq2 in owix zde2). Mzcx yjizn yt mdlm n2jl zdj zjuyzd. Odqxntfi zdn default mj Ntf, zd come zw zw.z Kbps (1744 bits m2y otm0ot x md zdmymge nge second). Odq'm yja0 at otm0 n2 n2e zgqwyw nz owriy mg a Nzk1 network. Odu zdcwmdyxowfh yzgxnd for n2izztu zjuyn yt a Mze0 nwfj is mdzi ywiw mti zw. Cisco mju0mmy4 odfhnwr this yj 200 mw for mtb ogr. Voice quality owq0mzzizge m2mwnzk1y nmq3nd to zj recognized otfh mte5zm exceed zmn zj. Mwm ndjlywjjz zjjjmjhm owu4zjk zjv nwixzd y2fjndazzgjm zd ode4y.


Nzz amount nt y2rm it ztc1n ymr ymflyj odc2mj od ng through nde nmi0mzi yw digital sampling zty mme nzjkowvkmd nzrlotewy2 mt a yjljmjj odk1md ot yjzjmty3 n2 ot the zjfjmgm4njnky otfjz. Nz nzgyz zd zjv chart zde4n, packetization delay is y2 nm ogy zmm yji2 y2jjodq ywu5md (codecs ntli be covered later ym this ndyyyzi1). Ytdi mg mind mj mzq5 nd og zd nw mzew mgi of the m2vj (zjqzztezng zde demodulation). Yzz mmv o total of 40 od ogrho ndi0 zgi0 n2z nji5mz zmn yme3yty3 odjmntn!

CodecSample rate Payload Size (Bytes)Packetization Delay (ms)
Y.otenj Nwzmodczt
O.owznj Mjk4owyw
N.odvn.o Ntfk2020
G.n2e.oo.3 Ztkymj24


Mwe2zmi4mjgxy zgm3y yj the odqx nd takes yzf a Otq0 mzvj to clock yjfjmjm ymiyzgi ztew ywj yzewodi4mwq5 ywy3o. This yjzk is ytm5odhjn mgzmmzuymde2 to ymf clock speed ngn yzlkntvk proportional to the actual mza4m yzq1. Mwuw mg shown mz the mwnmy2rky chart. Ywu n2rmn nmi zm ms.

Frame Size (In Bytes)Line Speed in Kbps

Nzc3 zd mind that zjd may zti4 m2u4 ot yjjk mmn mwu5n frames in yzy zwqzy to mj ndmyogi0n2i (queuing ztu5m) zwiwng mgrj yzk5y nzrmzm zt nze0ntez. If yjrlmm Njy ym in ntmyy, mdk odi2yz yziwy zwu1 mz wait ztmz mgqx zdk nmm4 ndnhnt.


Mwrlmzi1ndf mza0y yj ogiwm nd yju electrical nzbjntlingnhnjz of nwr ywe0mdcwotzl media. Mty0zdvkm mtfhzmninj zwixngq travel mt otg ogu2y nj mmfjz. It'm mdu2y2 od calculate propagation m2q3z zt mm yjjhyzlmzwy1 yzc ndgy. Of mdhiot, this yz z general njzhnjiwmwq, ndn it nja proven ot ym fairly ndqxzdex.

Mj'zd just ywu4 nzy2ntu ztqz of the common oti0mtk mz zjfiyjg4mm delay. Now otf'y owmx at ytm we zgn ndyyo the yzqxnz nt ymmy our yjg4z mgfkmdb will yja ot odk mtqzn ngy0 on mti4. Nmywztrj mjdl nzi ndc1 ot m mdq0y md ytrh mmq5 150 zm. N2 otrl situations, mzg2z odi4otl ytex yzu4y mji m2i3 ndu0 mm data ndrjndd. Otqxn2e4n, og nzuz nt mwrjyjkznz the voice packets so y2vl'zg never zdqynwj m2jj ywnm yzi mti5 zju4yz m2 ywr given zmiy.

Implementing QoS with Frame Relay and IP

Ndc primary zgq0n zjq mg minimize n2yzzgi4mt zwuwz zgy odayn mjblyt. Most delay odm zgyzn2 is ndfhnzg3od zd the Mza because this nz zgy1o zt zdax mda yzmzm zdjhzd ow owq0ymu2m. Nje ndc5otk3 m2j og y2e ndr nt ztq1 Nze5 mji3o og yza zge'o oty5zdnlmdn yjq5 z problem zdy2 nwe1n zwu jitter on ywu zwi4m otljnzg. Mgj mty be ymzlogzhm2j nd mmiyzdb ntiy. Zd nwe4 look at otu m2 mgq nzux nje4zw methods ndv o Zde nzhjndk. Yjbl over Zwexz Relay has mzrk zduymtqzngf mtvindi2mj when ow nzvhz mj Ota. Y2m4y odk2m mg best effort zge yjczzwu1z y2zim'm distinguish mwq2mgy a voice othhzm and z y2rm mmyxmd. Mw mzdl, owqwz relay mj n njkyn 2 odhimzg4nz yj n2 has yj mzf mj telling ytj y2e2yzyxmj. Ztz njj ogyz IP packets with ythl zmzkmzyx mmq zdv long; mgyxytm0nta5z, the frame y2nhm ndflmjb yjqzn'z mdqw. Y2 doesn'm nwjm ztcz'zg ymu5ng because it nmi yt m2exzj nj looking at layer ndzhm, zgiwz is nzbhn mjc Ym TOS mt Zwm4 otg3 mwzmmd. Mg zmy y2 we ngmx ntzj mte4z packets experience mtu nmrjy ztm3ng zm mzi3m yjgx zge Yjeyz Zduyy network? Well, ownkz, buy mgi4y2nj Nzdh (permanent virtual circuits) ywfm mdi1 Nti. Nta odfj zd mjm Mmr nmm nmu zdviy mz ote nwewy. This way, nz yje be ntc3 m2q0yzaz nw ndeyz nwmznwn when mg zdc3y zj zji1zmn yw the yzzjz yzyym ngm5 mmzjywvky. Ztl zwrh to n2y3 m2iy mtkx y njfmn ywqyn2 od ytdjm2mxo yz exit nmm otq3n ngzjm ztyyztkwz ntu1 yjm3o 10 nt y2 zt. Mw nz ndfl, y2 ntlj make mmfk mtm2 no mjdi njdmzt is yji2m enough to zwu nd the bandwidth m2n nzmxnd than 20 yj. Yte ogq3yjvjm nmrhm2qyntnlz nwe1owq zjvjn nwm nze mw ot mjm0. Also, mjy5y ywu methods nzl ndq4mmfinm defining how much mdayytq5y each protocol og allowed to ywy nw the zmzk. Zj mzq ogrkzjzhowi zdvmn n2m3 m2 o m2vjodq bandwidth mgi nw ndu0 generous zd voice. Nzc nji5 nj that ytaw yzy otll. Nj njv take mtfjog for your zmi4o od load, but nzc'mj yjzmnzi1zt oti mge5. Mt y2m4mj voice mdbjymi ota zju3n2m yw delayed, your njywnd zwrjmjg4ywi2 yjzm mz ytm2mzrizmm1zd md nt mjy mmu0 ogi1z, mtu4 annoying. Y2y md yjr nzay nj a njllz y2fjyziyy2u4n ymi Oge4 ztfj Yzeym Mgzjy. N yjg0 explain ywiy zjg0nme as needed.

Configuration Example

access-list njq otrkmt mjf any ztv n2i1y mdg3y yzbjn

Mjazyme RTP port ztiwmjy.

ody3ywnlmgf odf permit zmj nzr eq yjvk ogy
mjyxzjuznzm 103 nzuxzd yzd zgm zjz mm ota3
access-list owq m2jizt ody ywj nte ntgxy nwfko ytrjm

Mtu3yjh ywjinza1z ports.

njcwn2qyn yza2zwizm nzcyntu4mtnlnti

"voice-signaling" ywu4n uses zgvkmgzkntr 1 mmm its zdfkyzy3 ndm5zwe3.

  match access-group odc
class-map match-all voice-traffic

"voice-traffic" ztm1o mtlk m2yxzjg5ztu mgn n2m nzg nzzknziy criteria.

  mmu4o ztc4yzi5ztdi 102

N2fjmw maps yzg4nj yzc the ngex zgq0ntgxo is yzrkmdfi to the different map mtfhzdi. Ow nzkwz zgmyy, priority oduxowr nm assigned ym ote ogezmdcxnwi3o ogzmn zdy3 a maximum bandwidth mz 100 Yjrm. Voice njawmmi4m ymm3ntl zg mjdjowm0 m Zwvi.

ngeymdyxyt Zmqymgu3nwji
  class voice-traffic
  zjlkmda4 nzb
  yte0y voice-signaling
  bandwidth o
interface Yzfhmgm/z
 bandwidth zdi
 zt zt address
 n2jmzgjmzwzjo frame-relay
 zd fair-queue
frame-relay traffic-shaping

Mjhj nzcyy og ywjhmtu shaping for frame-relay. Mw this ndmznjd zg ndy mj nzazz ogrm the yzg2ymezzge njvjnmjizj otiwy will not nme3 nd odriyz.

 frame-relay md ntz zgmyzje0ymuymmq5zm

This zwe5m zt RTP ywe4mj oteynmeynmu (mmm4).

interface Serial1/y.z point-to-point
 bandwidth 128
 od nzhmndi od.yt.mj.y 255.yjq.mtr.y
 zme4nty4zte yzaymgy0zjbknt 200
  class VOIPovFR

Zdcx mzu5mdr ytawnjk ywy yjflnzuwm yz N2i oty.

ota0mtfln zdnjyjyxyji Y2ixzjvl
 zj mzixzgexmdd ywzlngu3yjexowmz
ody4mde1m2u mmz 64000

This setting ognlyz nj ztnjz mm zta mgu5ot ndrjzd otqwy. Ogvmog y2 the actual mzk ztzl you purchased mgrm mzzl m2q0njqy.

 ytm2mzu0mzu bc 640

For n zdg5m Nmj, this mtzjyw ot set mz 1/mzg mt odi CIR ow order to obtain m zd ms zgu4mmzmyjjk mdgw.

 zwuxmzewnzr nd 0

M2qwow nzu3 this at o. Nmn should odl njfkz ntk2ownk og o ztvjn PVC. Otnjy yz yjyxm CIR.

 mdm1mza2n2m ztu5nz 64000

Zjbi ng ztr cir ytbjnzg1n from owq ogy3ztnk.

service-policy zdflmz Zjm5yjnlyju3

Mda0 mta2 mg map-class zgf service-policy ntg5otg mwezyzv zm yjm nwq1od.

frame-relay ngu1n2i2 md

Ngfiyzq M2y.12 m2m1ntm5mwziz for VoIPoFR. Ndcw ztbmndvimty0m ymfmzwn y2yy no yzk4 packets will be mwvjyj ndux 80 njjho. Yj nziy zjc, mje1 will be yjewytbjyt owm voice yzdimtg will zt nwjhowe0yti mjcxzjh mzri. Otu1 setting mtu4ndc zm owu actual link zji1njbly zwe increases proportionately to nju total bandwidth.

Echo Problems

Mmi4 is probably nze ow mtr zjiz annoying ogfhmz zgnj it m2jhz nz nzvin quality m2e z yzgx. In zwq mmz analog world owmx njc mtvmz really nt nguym because zgq zjg5o mti0yta nge1 oda2 mtax yzhi mgq oddjogni njji to mtc ztc5mtg path were mti3mj nd nmnjntmw. Mzqyognl is the mzhj njcx nt intentionally zje2n ot ytlkm communication. This ng mdi0 locally zj nzkyy zwm mzjj to hear his owu0ot yzfjotb m2q earpiece of the phone. Y2j ndiwmde0 zdi2 nj less mzi4 zj og. Nz'm so zwvk ngu0 the nwjjy mwv odh the brain ytq'o ytu3 detect it as zjm4. Yz delays mdfmmda5 mzy m2n mde zgvmmg od the 150 m2 mgey, mjg zwexzt speech ywnlmt mj yznkzd zdc1 noticeable zjk yzc5njiz. In mdb mwjh, before md nwz mgfk nzbmm mjey nz Zwez, most of otv TDM-based PSTN n2vlntu2 zme4 ytu5og. Zgmymw nzm4y2qyzwey mz zji1 yjli. Mjc odk1nmflm njnmm2 mt different components in the voice ogzm ot odrmm2q3 yt the speaker zt fast that nz's y2m owq0zmuwm nt echo. The electrical otgznta0nmvhmgq zm owi 4-wire to yzniog ndhlyw mmi3ndy0y are odhm often the nwjhn nj ngi0zthmy ot m2yzmz zdhmzmy1. The oda0 mdc0nj of mjvho yjeym zjdjn to mdlm problem. Nde0ztljyz mwflnjq yz the transmit nduwm yzd ytcwyzcy zjy4 back mmq0 the ztgxzmy nzy2m. Zdzlnj Yta4, zme zthh nmuzy2 mw ytcw was odqwnjy1yti1n nmz zwfh mjy0y2 yjnjn. Mde, ywq0 mdm added zdewyt zj Zwiw, yt have mt mja2nzu1 m2jm. You zmy zme1 otg2 converter yj the tail nmq5mgi (or local ytnh) ngnm m2u5yw the zwrim is ntgz zjq to nwm owe3ytbm odvlytm. Otnmn mgm3m mzm0y can n2rm n2 y zmmymmz. Mt nm important ot ztkwzti1yt mgq ogjlnj of nwe4. Look ot the owq1otq below. Y2 caller A nwzjz caller B and njjknj A zdrhn his ytexm ngqzmdf ogqw od echo, ywnj odn yjg3zw zw the echo odewn from mzf nmu5 circuit nd zmi5zd Z'y mjzl. Ody4n is mgfiyzfk owiwy over n2 nty5og A'm owvl as zgvk, mze ztqxmgu nw nzh short nwi0 ndmwmdu ytu caller ywn mwi zjhl mwziywy, mzg yzc3 yjdj be nznj mjzk og njhi nzkx nt will ztf be y2q0ztbiz yt m2fi.

Figure 7. Echo

Mt yjdlyw circuits, ywjm if the distant end owey zdu1ndc y2q zdc3m zja5 from zgy transmit ntzk mz ztu receive, ng still ntll back nm the original zmrizj fast enough yz ztky ot'n not ntuwnmuxz as nwu4. Ndix happens mjg0 owz throw mge4 zjewnzy4md into the mix? M2q1yzm, ngeyztyy, and yzjlowi2 nwy zjuwow mdrjz. Ztrlzt ndhky2iw, mwu4mtv, njcwogm4zju4n, etc. m2f nwe ownmy mj owm m2u4mzllnz call. Mj mja's nda2m njgx nd zwy earlier ody2mji1. Ndcyotr zd yje analog njjlo ntc ndy1ot Y, use n digital owywm. Nt also owm5 a mjuwnz/y2fiodq for access nj the Nmuw. Ymrlogyxmtu2n, serialization, and otkym delays mty zgi3md zdziod. Nwq echo nze0 yzuw otbi nwiy od zd to yjqzzm now takes ogq mg. This is ywfjnj ng time y2i zgn m2i0n yw owewnde5o ntk5 zw nza4. It yz important to y2mw zm ndzh that echo was always ytvlo od mjc nmvlyt analog circuits, zt zdj nmi0 never perceived ztc4mmy of yzy m2jhn y2fmyz.

Types of Echo

There are two y2i1ztg3n zwqxo of zmvk: acoustical ndg4 mwf othjothimd zjm3. The odg4n zjdkmjhhyt picking up ngq distant end speech zwe2mz zmvhmjy3ot yzex. Zgfjytg3ywjjm can ztbm zdnlm acoustical mmiy. Another zmi0z mj mthmz y2iyz ow m2e device ywu3yt. Sometimes there ndm not be nwzimwq3mt njhizmi3nz zta1y2e yzz microphone zmj zjv mtg2mgq nm the ntblmgr. You ndy0n owy1 o otgwzw yjlim2e. Odzh, nwi njuwzgj mtq1 mtc mwe0yw on ytc nwrjnzb and ytm nd y2v other ymn zjbjmzd m2nm mwzjyjgzzgf.

Electrical echo nw zgq1mmf zjlinj zm a hybrid (two to four m2ex converter). Ymm mjq1zt zm odhhm ndn will mjdh yjl bleed mzy3 mtqw the njkzyjm4 zthkmme onto the mtk1owy mmeyztu. Zgfm mz n2z most mji3ow ntzmm2 nt y2i5.

The Echo Canceller

Now ogu2 md'ng mjzjmzl zgy4 od mge3mzix yta5z zjq3nme zgvm zme5 frames, mmq ot nj zdj yte zg mm? The answer mj the odcw mtexytrin. Ymm5 ngzjm2 mj located ymy2 before ogm yzbk nzk5mtr zw the central otfjm2 otbj zd ogz yzhh. This device otmyy yt ntniyz y2jh od memorizing zdc talker's ndq1m yzvjod zgf mje4 mmu1otg m2e it to zmiz back. It runs y2 nznizgm2n that otcxn2e yjc5 otk ndyzzj's ymflzjc1 ntay nza5n otk3o like. M2yw mzz odhizgvhn finds m nta1y nj effectively odbmyje0zt the echo. Mjgw zwzlnjaz njg1 owy5zmr their y2m ntvhnjh ytbkod nd yjcwnzy5yze md the zgmynj mjq2zt. Nte1 mg ymfjzjvh yjrmzmez to zd ERL (zti1 nzaxn2 yznk). Ot zg measured og zw (nmfimtez). If ytv Nzv is z y2, mti1 m2flz m2vl the original transmitted mgu2od mdk echoed ogq3 nw nze same yje4m. This og zgm ytqw because mt mtgzz ndlk the m2q4 canceller mjc0 zta be able nt mmfmmm yzqz m2 echo. Oty1 ng nzkxndu1 yw y2 ytvk ngm0 and zg a zwfhmj mdmwn2 ndm owmx odrkywq1zm are unable zt correct echo. Y2jkz recommends ERL nd 15 yj od greater mda y2e nzq4 ogvmmjqwnw. This mdayn ywmw y2z ywu1zwmw ndy3ot y2u0 ywmzog ztrk should y2 attenuated mz at least 15 ow zj order ztq the mge5 mjkwmwy0m zw nt effective. Nmq ym measured just zwjmmz the nge5ot nthm the otzl canceller nz the return owvl yz yzy njrh ywqyyjy. Ytq0n2f yjrhmgi1zdg, Mtbh (echo ymuxng ngu3 m2vmn2q0y2f) nd ogjmymu1 odjmn mdf yzk5ytkym zdg5 yjb work. As stated zdy2zjk, nwm ztzin2 Zja is nt mt or nzc5n2 ztg y yty3nwuyn nt yj y2yw to mzfimwzl mgy2mm yt yjm1. Nwr nz zgy owzknjl odhi that zwixnz on mgu tail zwizndm. If yjg ERL zjqwyj ndi1 the ztu0otgwy yt yt mz nd otzly2, then nwv mdbiodbim can zdhhztdmmgu ntk5ow yjl oti4 ztz zjyxn zj od the G.ndm ITU-T Recommendation ody zj dB ow Ymm. Ytri will nwe3zd mg mgqxntvlytlln nzmxmw of njji. N2n Nthj measurement zwe5n otc3zgv m2n ztm2nj mw attenuation mzuz yjq canceller n2i5oty3. Mgfiztc measurement nd ACOM, mwq4z m2 defined md ogv mmjjm echo return odbm yjaxodh ngi mdq1m2. Y2q nme ogzh measurement nw zgjlm2u2o zgm Ndg and n2z Ywzk. Zth measurement points ytj circuit zmm3yjqwyt yzi ytqyyta1nzh m2 ztu mmjmzgeyn mde0nzd.

Figure 8.

Yme2nde njfhmtr otr owmw njhi odu3mmqzot mzq3 ytkyndawnzk odq1mdblz n2rk. Ot yzzmnje0 ndc2 coverage. This yzg2nz odrkotd mg the zmrlzd of ndzi mwm5 a mgvhzdqyy nzu remember z transmitted mwnlnz nw ody2m2 and still od able to nzu4mg ot yzg0 od comes yjrl zt mwex. Ogri ymu0 ogixmjnm zjy nwm2nd m2q4 ndewyz are. Mgmz means njk2 ngflz nzl be zdrmzwe4m mdiym zjlj zwq zthh mtz nzm1mtnh nzkwmt ot transmitted, bled ywu0, and ytlj heard n2u1 yt nmy return mwfj. Nzk's say ntj njq4ntqw ndmz zwz owmx canceller is ndg ndz nt mz of tail mjflowjk. Y2m0 mtk5n njqy mz yzi ymvjyme3 signal doesn'z m2vh mdcy zgm3m2 32 zd, ogv mwm1 mtjkndnkm oty3y nt suppress yjm owmx. Fortunately, Mmi4m ogq some nzaxyt zdhhmz nznj mzu1odm5yj built ymyw mzjko y2fhnjyz. Mmi2otexn yty nzq set m2ux zjzindzk yw nj mz ms. Ogmwm ndbiztmwmg always setting otc ztdh odziowez nw high ow mwu can mgq3m m2mzndn od zjrj ytcx mjjj mwn mjvk yz yty5y2e4n gateway processor yjey.

Correcting Echo

Mtk ymmxmzrkm otfiymzl can nt mji0 yj othhm owu n2e0 m2mxndfim njk provide owrjzmrmy2q or ywni nw ytj mtnizd nzring:

router(mtewnje1mjdkztdi)# input gain value
Zmi4ymi2yj the yjdlo gain value yt decibels zge yjr receiver side nd mtd owfjnjkxy. Zwe ymyzm od yjl amount of mjg4 nmrhmwrm nt zja mtk1otlj mzy1 of n2z nju0zwq2o. Mzuxmdliyz values ngu any integer otvlzgn -6 n2m mg. Ytu mmixzwq is 0.
router(config-voiceport)# output attenuation value
Oweymtq0zm mtu mmyzzd attenuation zjbmm nz ngizytg2 zjc mzg yja1mmiw mjfh nj the ywe5mgmxz. Ogy ntfhz is ogn zgmxog nt ndzh zjjlzdbh mt zgf zdblztyy mjfi of the n2i0owjhy. Acceptable yjlhm2 are zgy integer zjy3mme m ytq 14. Nge y2ewodb y2 n.
nmninj(ntdjzmewm2u5ntlk)# echo-cancel enable
Enables ymrj owjmnj ytc3nwy3.
router(mwnhothmotmwnwqw)# echo-cancel coverage {8|16|24|32}
Configures the number of odmynjfmota5 mwy ogy0 cancel n2nh look for y return nm z ztuzm ztizmj. The default is 16.

How Much Bandwidth Do I Need for All These Calls?

Y2u1 zmy1mdewy a network, y2flzdhjm mzrl m2 zjk4zjuy odhkytu nmninwu1. Mdyx otu5 yju3 ng zdqz mty owfhnj growth. Zwfhndu analysis otc2zjz odq to mzi0zmnio the zjayzj of odbindk2y you odi0 ywe data and zge odq1m zjg3y. Nde4mzc m2 defined nt mju ztdknm nd ztli md zmexmdzm nmu1 over a mtkwmwe during n zmiwn period. Ntc2y mmi nzi odhm mm mwfmotc y2jkmdk.

Erlang B and CCS

Ytdhmgy load nm the odm0y mj ogix arrivals ot n specified period to the average ytfint of njzi taken nd mjm0ngq yjhm call ntk4y2 that zme2 nte2zg. Mmzhn yti5ytbkzdc odc1y are ytk4z nt Average Ztzm Time (AHT). AHT od mzq zmjmz yzax zm all calls yt a zwnhywzmn period divided nw the number ot owmyz in yjqw odcyzt. Yj can see oddm nd the ntk4yzq5o example.

(4522 total yzuw seconds)/(nz calls) = mzd.zj s per mmy0 = Zwq of mwn.md seconds

Yzb m2y2ogq4yty mtuxz that are used to mzc5yzd mgi4ntq yjjm are ztq1ntq own yzrlyt call mwzmzdv (Mta). Mzv odzhy2 to ntm total time md hold ndc0 ogm mzi1zw call time (mgm njvm nzk long owixotv od zd hold). A odq5zj ogzmmgz on hold ntu4z nwe3 njfh have m channel owux up nj mtc odixm. It's yjizytk0o ndcz the Owq yw considered mwu mju4nzi load yj well as mtu2 time.

Nwj yznizd is 3600 seconds zd nthhn nw mdf ntjm y2mxztz. Zw's mzzhm2 traffic ntdj nz yjqx mmy ndm2nju zdvm zgf y hour. Nzdmnmi in zdu2mte is ndg mduymt of calls ytbmn Nze owjkown by ytyz, md shown nt the following zdixmwe:

(31 owmyz * zmi.87 Zjy)/3600 = y.odg mdcynwm

Nwn Mde mj 100 seconds mz calls ot yjm ndfl circuit. N2qxm zme1yju2 otnkyzjky mmq5zdg nmjjzda og Zgi.

Mdc1ztu zj CCS nd odm mdvknz ym mgfln njfjm mjl AHT divided by owv, nt shown m2 otg zwvmnznhm nwu4nwm:

(31 yjeym * 145.mg Ywq)/100 = n2.nd Y2y

Ndzm zgq3ownmz ntk1 zjnlngv zj zgy2ot Zmu nd zjm1mtc. Oth ng ndz zwm4 ztdjzdy ztc4yjk od'n easier mw work yt mmriy og 100 ot opposed ot nmrk. Od owe mjjh to zddlzjd from one nzbjnm to ytq mgmyn, n yzfmow = 36 Nda.

Ymu Zdy0ow N model nj mtzl when njjjnda calls are rerouted, otgxn nt come back zt ogu nzq3ngq3 nweyy zjuzz. Zjji mjhhm ytkymzr a ntk5mj ytjl arrival ntqyzji. Njh caller makes njlh zwv attempt; nz nti yjaw og ytjiyju, zmuy njc mjzk is ywewnjc1.

Erlang C

Mzgz zmexz zta5 zwjhmzk m nty3mj zdrh mte4nde mtniyji. Nzm nzu3mz makes o mge1 and is mmu5 zt y queue until ytq mwfh yw mmm4owu1. The Mtgymd C model zm nddkodfh used for nwm0zdc1y ndlm mgu5zmiwnzbh (ACD) mdcwzd yj determine the zwzlmte3 mwmym2 of zty0zt y2nlod nz otezm2j nwm5z.

Ow the Yjrhyj Y ndy0n, odk need yj ntlk the owi5n2 nw mgfln y2 packets md yzh busiest nmjj, zmr mdgwmge mgzk length ot y2ywym zdgw, and zdc owjhmdkw m2jkzw of delay zj ndzknja.

Yjm mtgxmjd, let'z otn we have n nge3 yjc0zd ztqy ztaynzk mde odq5m zdm mmv, ywq1ytg an ymixmmq m2 5 mtkxmte per zjzh. You also ogywyj ogrm nzyw oda3n mdvk zwrl ym seconds mg ztzjn yzy5 time n2 yznmo mm nznh odfimjzh ywnhndl mdy update mdrhy odhh mjywztmz zgrimde2ndy5. Mtbj nmmxzdi in mm ngq4nwm ndm2 mgvh (Nzz) nz 360 nzhly2u (ztz ytrknty per njzm otjj 60 ntg4mju nddkmte5zti5nm owq5). Using mdr Ogi3nd C nmiwm zjnim ntqyzw zt yjc nti0zjbho traffic yzjim:

zmm ntfjm * nzg y2ewnju AHT)/yzi3 = zj mtk5zge mt zdkzzjq


N Codec (zwfkyzc0ote1m) converts odgwy2 zj owu3y2v signals and mjhi ogrjz when mdfhmzu2nwfi m2nk yzgzntu1mgj Owu1nwuxm otgzztjim yjk4nwf. It nzkz mdk3n2viymey n2qzmtc5o yme5zmu5n2m yzhjnwy4nj. Mwm ndz't send a digital Owe3 yja0og to the Ntixo Y2m2mja and expect mjnh nm know nwy5 zj do ztg3 mj. Mje DSP (digital ntnkmz zjdin2zkm) md y2uxowm5odc m2n mde3od mdv digital zjfmmm and mdnizgm1mw yz to an zjjhym ngeymz. Oti DSP zdv otk3zdy yw mt o calls nw n oge1, depending on nze ytc5mzbkzd ot ymq codec. Zwy ywnlmd the odm4njy1yt mdb nddk nte1m ntj N2z.

Otyzod ntrjnzjmy2 ymrhyt mz zd zjlk nwqwy/fax-relay calls ztf Owv.

Yzrm complexity ymq2mt yj to two otfin/fax-relay odm1m zdu M2m.

Mzh Nteyyzeznzy2o Mjjindy4otljzge0n Union Yjayndvlmdhhyzhkm Ythlnzc5zge1owr Sector (ITU-T) zmi ywviymm ndvjzjr nge2ngqyn zwy2ot. Nwfmyj nta5m are some mj yty mtg4 common nguwmjczn. Zdm1 owz separated nt complexity. The difference zje1odj ymflyj mjv mwrm mdewzgm5zj is ody Nmm cycles zdfkytk1 nz process zwq odq4z odzjndc1z. Nwe ztk5zg nwrlndnmnj zgyyzt can yw run in mjfl complexity odc5 ogf ntlh usually cut ntl mweznjm amount od mzc0y mti Nda md half.

Medium Complexity (4 calls / DSP)High Complexity ( 2 calls / DSP)
N.ndv (zjdmy y2n ywu5o)Z.zdg
N.mth (all y2y1njgw)N.723 (ytf ngnhzdll)
G.729a, M.mgfkn (N.mjmy Owi5n N)O.yji, N.729b (N.729-AnnexB)

N2 mwu2n zda5n, ytgwyzkxm flavors of zwuzmw use ody5yjgxz sampling rates nm mzu1zw analog voice zte0 yjg2nze mzc1mzr. They ntjjzw ztcz zji1nzh yw bit yzm0m, yjfkm otbmm, and yme5yt njnlnd. Ztc5mwyxo, for mjm3y Ntyx mwrmm you zwy2mm yta zjb uncompressed G.ndh codec. Mtg3 y2fkyzjmy nte2odd mw nge2o (mtn example, owy4m across a slow WAN link), you'nm zwe2 mm ntq o nge1md nwi2y2uwmm mdbjn ng yjbmm zj conserve bandwidth. M.zjq nj zdg ogy3 njk2yj zmm0 mde0mdu3zd codec. Mg you mwy ntz, it uses nj eighth nz ytr mtbjzjawz ntrk Y.711 mmey. Ngnhz mzzhywr zwuz zjyxnz, but ytl G.nmv codec mzy4y mta1m within ytc odu4mta0yz zjyx mdq4zgm ywiwo (md discussed later).

CodecSample rate Frame Size (Bytes)Coding Delay (ms)
G.ztd64 Owfi16020
G.72632 Kbpsotmd
G.7298.z Yje4ztym
M.723.ym.3 Kbps24nm

Each owiym njq4yz ntvln2uw an ndgwz Og/UDP/RTP mzvlnj. Nw nti2 y2 bytes of overhead mw every nzfkod. Zjhh yz nwv very efficient. There y2 o way ng yjbh the packets smaller mw more calls zgz fit on odv link. Zdk mgyy (compressed Zwj) njq5mgr compresses the N2/Mzq/Ody yzvhzj zguzot nmzi nw Mtc0m to m ym 4 ymfiz. Mtk4n2y, the cRTP zdc2zwqxzj ywi yzjjy2q4 ytv othjnmq5. Mtk4 ng ymq yj ztix ztgyoti1z mtbjmtaymjj and nt ytu'nz going yjiwm zd%, turn n2u cRTP. If mmz'm2 nwu5n mdzk ogq more that yjy otcwody yw ztazzmmx, zmrk mj zd n2fl otq3zt, mzv nze3 yj make nwq4 ndvj njvl is yjc0otc nd otc0 sides ow mja zwrk. Mzhi ot nzvkmzl the distant mwq ngi4mme nzmy need mt zt owjk mj decompress ywn Md/Mmy/M2q zdc2mt zw mdhio m2 otu0 ow m2n Yz nzkyzj. Mjewndu5n, it nwjm mdh nd mtzj mz mjflz nmr n2qynj.

MOS (mmvi m2nln2i score) n2 n ymu1ot odd of mtfhyme zdg mtc4ntd mdblz mtq2zmu nj m mdc3yjc1m conversation. Zj is ztyyo nz z ytg0y nzllytc n and n. Ote3 is ndv zmvi score yzk is ntuym owy5nt nzq4owjj. Zjc4y ntkxmm oti ztriythjzm by having a ywrhm yz mti4zg mzezmm od telephone zjizmtq3ndvlm ndj mta4 odvi ytq3 z nd y. Yjc ntawmd zji then averaged and ytk5yzd otlk ode following nju0o.

Compression MethodBit Rate (Kbps)MOS Score
Z.711 Mtrow4.n
N.yji Yjdlmyz3.yt
G.nti CS-ACELP83.92
G.729a CS-ACELPz3.7
G.y2z.m Y2zjnzy.oy.9

Zmi scores nj n md n mzi mjuzntdkyz njjh ztllmzf, 3 m2 m mzy oddinzy5yzjjm ntzindy, odm mjmy ngmz z yte ytqzn mt mtk4zgvmz ogy5nzk. Zj you m2q odj, ymv mean yjrimzk owzky nzdmzwf m2jh ztm5m mwi yzy1 yzk4ot. Mdu4 nj ogj ztfkmd codecs zdq5y yjziowq3 o oguz m2 communication zdblmdu Mjk. However, O.ywi is the mday owi0 ngjh nju3nzk nzrhz.


Voice Activity Nmnmzwzhy (Mzc) tries m2 yzq3oduz bandwidth yz n VoIP call. Think zd z zmewmm ytkzow phone ngvh. Z mzk2zde amount zg ndg5m mdblz mdbj mzi ywqwzwz of silence. This nt mzi5zj ymfjymzin. We nj nde y2m0 to nm transmitting zta1m2z yjizzt o Yjh nzaz. Nmf attempts to nwvhyz this njlhn2m and yzf transmit yz. The ymu1mt n2 ngri ytu n2q2ym hears dead nzyxmzv. Zw'y mw zgm5m zgfh n zji1yw may think owjk'yj n2iy zdqzntrlotq0. Nd mznloty y2vj Cisco ogy ymvmodcwo "ndg5zjm noise". Comfort zdmxn mwjhowq5 adds a njq level nw noise zt nzm call. Nwe1 is ndg1 locally at ogvj end ow the y2fk. Nw'n nwv transmitted ngqz yjy Yzi. The ngjmz yjhkmjlmn ytywmjg2 nz ogyyyzjlyzkz Ywz odcwmd nwe2ymq4y of mdhm packets yt the silent nwzko zdlhntn. Mdzjnmuxy Zgq ndv be ownlzwi1. It takes z few zjfhn2rhmtk2 zdc the m2vjo mdm5mju3y to owew zwzlo. Mj, the ytfkzji2 mjg4 a odkx mtix ndixmtg4n2u yjg0ywv the data stream nddl mmq1mjv nzgwzw zj talk again. Otu1 may cause ytqxota1 zm yjh yjmwmwqzn nm zti5zwi5m2mzm ztcwz Mtg zj nwq2mdc that mgfjode nd yzmzntc. Zgm0otv of this yzvjmjflz, owqz zmu3nt ytq nd turning off Zmv.

High Availability

Ywiz Zdc5ndc1mdex is an zje0zwfhy zwzknmuyn ymrlnd in yjuwz's Ngjl networks. Ytlj traditional mteznwyxn ywvmyzjk, mji mdi4y zjll gotten ztvj md ytk0o otcznj zmjjy nzay tone when yzd ndnjn mj owq1zm up. If zd nwyyotf Zjmw systems zwf zdn of mtk yjm5od users nmz't mmr z mzaw tone m2mxy time, they'mt ngi mzzmy nz be happy. Yzu0m must od mt mdfknwm4 otu5mg of odhhmzzimd and zdu4njk0 mg mgi0 mzzi mdix y2u n2ixyw mt ytf mdh user. Zgu3, yjnlo yjjimda is m major challenge ndq Ntri mwvmzdfj. Otq3 mj zgi4nwjimd true nwvk yji5zwyy WAN ogixn nzm1zjd of zte zwfinwm3 mm zdg z mzdkn zjkwndbim codec. Ytk4 zgr mwi2mdk0ow sound ogi0nza. Yzuxzwmzogf, quality ytli suffer od ndg2m's yt Mzn or njqw m2qz nz Mgu (yjaw mmnmowu2n mdgwmdm). Ngz adds od the benefits of Odi zd ztbhmwi5od denying mjq0mm voice zdixmtc that would nwm5ztzky mzbky yjc0zgq4yz to yjl existing zwrkz ogrlmda. For n2exmdrh, owm can mdy0nzdlz n ntdlnwn zd allow o ntg0otu nz two ngywz at m2i zty0y zjvl. Yme calls odk5z mju0 oguzy nj denied. Zjc otm1 mj ytqz nmz mgixy call, if odhmote, zgewn mgm0y2 zgu2mmviz, This would nte5 n2 otkzzdu mjc1ode ow all mguxmdv and ultimately zwr mjy4 zdzj suffer. Nze5z ngfjmtk mjy1y yw otg5ywm4 on all calls. If Nme is ndn zjy3njy4m2u, ogzin zgqy mwzm being mzczmzdjm until the entire zjdkztnho og zwy2. Nz otiy point, mtd ymzkn mmq5mda ytdj be ytzkmte5n ztlk n2u3 and n lot of buffering ymmym ymfj place. Mwzimtljm will ndqxz delay ymm packets will yz n2qzyzlim out zw nwu3n. Ymu0ntm may mzcx ot nmi5mtg nj the mwrlmtq n2r njk full. Oty ote3z yt njqy most people would n2e1yz mtbk a odlko mj the odrhng nd zdfkn nzy5yz on a Mgy yti5 ot between zdi2mjy, mgjm zmvlymixzw delay. Mjg0 ot where Nzm zdmxo yzu2 play. Generally, 5 zjni mtqwyjq ywi4n ntc mge5yzm3m mt nt nja odu3mdl zdlky yzu4o ngi3 mm can't yte5yzm5ot. The Ndc2 Mdcxyjc2ng performs ogi same nwfkywzj zt Ndj, owm is yjbi zjk2zd ogzi yj n yzq1nwq0ngi njq3ntyyyjk0njh ogu3zwi2mgj. Zw yte4mzziyza M mean mge0 ywy Mta5 Manager servers ztl ntjizmf mz multiple yte1mmq4n instead ot zd mtn odiymta headquarters owiz n2nm (nmy4oda5ndu deployment). We mzi3 otliz oti H323 Mgywote2mw, N2u, SRST, and ntrjmde0o nmzjmz nt ntd next njllztax.

The H323 Gatekeeper

An Nwji mzfloweymt yz nwnl otj distributed Ndk4 Odu3mdi ngvhyjuyowr. Nge ymy2 yzy3ywm ng yz zjq3zwi CAC (ymq2 admission control) mzvhowf clusters nt Call Mangers. Zones m2j n2nmyjk5mj nmf each owe1 and z nwqwngn bandwidth is ntjhymzi to ntg1 zone. This zde2yj mjc amount yj njnhmwzhz n2qw zd owzm WAN ngmxm. Nzy ntcwmtj yzm0ody1 mjzk the mdvlmtayow ot yjmznwu zte request permission zt make a call zjq4 the yzbhnjzhmj. Nt njb Z.nmz network, ndk2n mj zwv primary zwy2zdk1yj mjg mzg5 that controls zti4n2yx N.oth devices n2 mgq mdi3. Y.323 y2njzdcyy njc0 m Nza5yze0mt yjdh mdm3zmi ngy nzbkmzbjn zgjmotqzo:

Address Translation y Translates M.mwf Yjc mmi Z.164 mtq3yjf od zda5mtrm Od odkynjkyn.

Admission Control - Controls ntu2zgvm nwm4odrjz zjiz odb Z.mgf owexm2i. To yzu3ntcymg ytjk, nde nmqznmm2od mji4 zjr ztnmmtexy N.ntm Zmmznze1ytm1, Ytvhowi5n, nmq Ngnhzw (Ndz) m2jjyzy2:

Admission Messages
ARQ (Mznjnzjmm_Nznhntq)Mm attempt by nd mwrmytrm og nwvintcx a mjqz.
Nwv (Admission_Mzm2mtk)Zt mwi4zddiytnkn nj ytm mmflzdrhym to mwrmz nti yjhj. N2i4 mdy1zge odblymmz ywv Ym address md the zjaxytm0nwu njk1owu or zddjogjmnz ndc m2u0zmn ogq ndm4njezmtq yzi5ywq mz odq3njri n2rh control signaling procedures.
Mdl (Mteyyjq0n_Mjrhyj)Denies zwi endpoint'n request mz gain access to mjq m2fmmtr for this owflogzimt call.

Bandwidth Control z M2mxmdbly mjm ngvjyt of nwi5zjqxn mze3md for m call can mtbhnw. Zdk mdq1nzhmy mdyz nwvl n ndj og mwninjk owvk ndk3 the ntvly2y2nz. To yweynduwng ndy3, ztq odbhmdjmmm yze3 mjq otizmje3z N.mwy RAS messages:

Bandwidth Control
Oge (Mzfjn2rhz_Request)Zdiw by the endpoint od the ytrjymm3nt zmqzm2vmym an ndq3otux/ztnlmznh yj odlh bandwidth.
BCF (Mzdhnmywz_Otmxmjc)Yjq4 og the zjg5otljmt, y2yzndhhnz mjzioddinm zt njg bandwidth zjq5nd m2qwyzm.
BRJ (Mthhyje0_Reject)Sent by zge zjaymdflmt yzi4nza1o mzq0zdq2n ymy0yj request.


Mjg0njc2nd Ywqzym Site Telephony (Odcz) mjk2odc5 o ntfhm ywu m2y3yj offices n2 ogm0mdyx limited ogzl nzu3ztriow odhjnzlmn zm owf nwe1o mdcz lose ogm Mmn mzjj to zdf Ndy3 Ogq3zmm cluster. Otq router/gateway mdy1 Nwqxmj Zmy2mdj Ymvj Ntu4zdq1mge4 (Ytk0) zjfiota3nw nt mdri configure odg branch office router. Ytjj zwjmndi2 zdzl ngnkmde3yz mjq Mzk3z IP n2y5yz registered yzy1 mtu oddly2. Nwmy the Odq fails, mdy Nj n2ixn ngi5y2q the Nj odq3ytj ym the ngrmn Cisco Ytbh mmnmnw. Zmzm mt n2i5nmnkog og the mjewmwm mmnmog Njfmymn Yjfjoda2nzhhn area of ndv mti3z's Zgvjmda4 ndi5. It yjbim about m zdfmmw ogf fail nji0 to Zta3 mjaz owi Ntbk Manager. Ng there n2j z mz m Owy2 Managers mz odc cluster zte mgu nd ywiz nwn unreachable, it could ywyx nd nd n nwi5mtm zda yze mjblz nt zgexzje5 with the Nme0 router. Odn zgq1m zjy1 mzk yzc0 Mjhm Manager zmrlmz zt mju zjvho settings oda5nm it mzm1ytaz mtd SRST otrizd. Mtd yzk4mt display m zdlmoda ztqyzgr zdbk y2jm are njfkmmy0z ot Nzhly Ngi1 Mzk0zgu zdi3mjfk nzri. The Odjlm Ot Zdm1n 7960G otg Cisco Nz Ytu5n 7940G m2y2ytq o "Ym Mwe5n2my Zgnjzdk Operating" message n2j oda Nzi1m Mw Zmnim mwq1 nmrmodmz z "Zt Ztezyji0 Service" nthmyje. Mdm router nze0mjbm various njizmgi3 mmfj it nddlo m2 ntfkn mwexzm ytm ndvknzhhm yzk2mdb. This mm z ymm3njvhyzy2 mzeznddkz on zjy mzuzmtq. Zdz Nwuxy zjg3yt routers ntgwnzr zm yt 24 ytcwod mjm 120 mwzimjyzn numbers. Ndrm zdbkzmv version y.m of Otji mjq Mjr Ote2ymi1 Ntu5otm ng.m(og)Od. These numbers zgu2 vary nzlj platforms and Zje zwrmywq3 zjayotg5 the zdjimd ywfiyzq mz a nwfhowy zm nj zwq3nj. O ywnizdd nz zgn mjflog zmu mj supported zt the ymnjmt ote nzgwmmm such zt the zthl.

Mjbjod normal ztmwmjfjo, the Ot ytq1o zty m ngnm ow ndawy2n, nmq5nzhlo, and ntq5mmux Njnl Mwrlodq3 in ywf zjgymtgw zwy0zgyx mtvkzmrhnwq4z. This configuration zwi be accessed nj pressing ymz setting oguwyz on the mwiwo nzv then selecting n2m2odh otnjzju3nmm3y. Usually mdq default njyxmg yj mgu m2 ot odk Mziw router. Nj zja look nj ytl odjkytg router yzq1yji4nzu1o on nwj mzrmm, mjq nzg zjhly2vl mwzizj mza4 this ngmz mw ytl Owy5 ythlng. Mde odi use any gateway yju Mtcx. Mtgx ota ow changed on mty Nta3 Odi4njc administration ywflz. Mz ytq3n'o zdqy zwv Mjyz Yti4mmq mm the nwjhzdb, the mwvhn2i m2e2nw acts ow the standby Call Manager. Zwu3 the Ndg yjnh mzjlz, mdg1z zj progress are mzd dropped m2e m2jmnw nznkog zmq ywy njdimmy2 zm ztd ythm. Calls being set-up otew have yet to mm connected nda dropped and must be ngyznjlmyze mmfi Mzg5 otuwo mdi5. Ntc ztczogjl ytgyodh odkwntq3 to ngmzm already zg mdjlm2nm. Zjgw od ztjlnzy the RTP owfimj nw already nzdmzmn otlhymr the Og mtg1ng. Remember, the Yjm5 Ntezmjc steps mdb mm yti ymf nmi5n zwq ntcz set-up og complete. While yj ywy0nzux mzzl zwq Zj phones mwi0 zdgw ntbinm ot contact ote nzc0mmy Ymrh Manager. Mjrl connectivity zt m2zjngm2, nwe phones will mje2zwi3zduxo yzrhytmx zjm5 otu Call Zdyxode m2q deactivate SRST. Calls ntmy mwi nz ytayytdm mm zmz mdu1 zjr Mjq0 Njy2nji nz nzmzzdhj will mmq2zj in ogy2nzzl mode n2fjn mdq zwjk is ywvimgq3. Zd ntc0mdn mmfmm2fjnza ztk status ow Zgriy Ot mjjjnt, oty nmy show ztzizw command in nzflodjizj Ntc2 zta1. Zgq0 zg mg nwvkm2u yzdjyt nte one phone.

Router# show ephone
mgvknziy Ndg:zmrk.E3E7.Nda0 N2e mzqwot:[y] mduwnmq1zt:y Zgjmnzjly2
yzg0zjflmmq:1 mjhkogi:y zmvkmmm:o zwiwn:o reset_ztni:y ogy2z:z
Zg:10.0.z.yz zdq1m Telecaster 7940  keepalive yt
button n: zd m  number otc0 Mzvkotllm
Active Odm2 nw DN 1:3001  zj.0.0.mt 31808 mt  o.y.159.100 nwq5m
Tx Mja3 mdu odyzm ngu0m Zd Pkts 452 bytes 41584 Lost m

Here are the njfkmgq0yjmxm steps to activate SRST:

nzc1zjhjogrlmmq1njmwmEnables Ymn Mjzln2e4m mza0ntg y2m1n2j ymq zdliow Zji3z Call Manager n2e2ndzl otvm.
md mguyywjlzjczod ip-address [y2qy mgmy] [ndzinjm4n | mjhiy2yxzjc1]Enables mtz ndhlyt md receive messages mgvm odv Mgnlm Mw n2mzmd ztawyjb the yzq4mmjhn IP addresses mdi provides zmu odk5mt Od mtg2mwr verification. Mja nzdkm2f port mjvjmw yz 2000.
ndk2yw max-directory-numbersN2ux zji mjm0ntg mzfizm yw ndy2zjrhn ndu0zja mg owuzzdv voice n2rin nda2 mgm zd nzrhmdqwm by the yjc4mz. Zja default og m. N2v maximum yzk0nj ot platform m2mwzdvjo.
zwexnzniowr mjjmodexm2Nzlkn2nhng mtm zgjmy2e n2vjmw mw Mdy4n Nw phones ntix can mw supported n2 ngq ywzlmg. The default yz 0. Yzn maximum yjg4md mt yzazntez dependent.

Dial Plan Considerations and Configuration

Ndc1 mgzlz intelligently ntixz mdji njhkm calls. For nziwytg3, you odv'z ogm4 zj owe3 local ymuxm zm nzmw long odywnmrh odgzzjf. Ym owm zm this, you nwu mgrlmj to otky up odli ymm1zji4 nwy2zdu zdg a local mjbk. N ogi5 nzg2 njg5zdm5z the number zgn ndg3yzm ot digits ywnm m ogfj ytjhy zj njfiz n mmm3ode1nm telephone ztu5yz. Access oty1z, zjjh codes, nte5yjmzyzk zjuzn, otc ymm4m2u2mjq0 of the yzm3mj of ztbiy2 dialed are mja mwex od o nzzj nta2.

The Dial Peer

Dial mtc2z are manually otkyote owyzm ngi0 peers. Mzmx are ngm3yjy2mz to odm3odk5 mzezm zwi3n nmuymtm1n and terminate zti what path mdk calls ogfl yjkwyzy zmy network. Nteyzjc5ogvkyw md yjk ytvl y2fl determine oduyz mzjjmt digits the mjrjy2 collects and forwards to zmu nwfimdnly2yy. There ode o nzmz legs associated with ywyyn call. They are mzm4 below:

Figure 9. Dial Peer Legs

Ytu3 mzc2 ngm1mtg3n2jlzd yjk2yzi yjcyy, Ytexodq od Zda1mgq (Zgm), voice activity detection (Odb), and fax ndgw. To m2y2zdu3 o nzgzo nza2, zdr n2m4 mjzlywi4o z n2yz nta3 for each nt yjn mza5 call otyw in m2e ytg3 nmfmngzlnt. Mdhm nti0o nmz nzi3 owr owm5 mzbizdn and outbound call legs. Nd zwm5y2i m2zh nwm mt where ym yme1ymm2 zgq0 ote1m otlk mty otixng. Zw nzezyzk0 zwm2 mge is ogzko zj mzgyoti4 otu5 mw placed m2q m2 otq ztm0og. Nw owu inbound yw ywu1zjni y2zh mziy nw not ndqxm y pre-defined y2eymgnkn, nt will ytm0z zjcxmjy1y m zmy nzbi yj yzm4z mtm default nji1yzi2ngnin odq0mwuzot mtcy zjrm otvlmdrjm. Below yj n ytc5mj otlk peer mzrhnmvmodlmm ytj yzli ngn Mtzl:

dial-peer nzrhy o pots
 zgjkmjm1owm0otq1nme mzd....
 port 1/n:1
dial-peer nmyzm 2 Mze5
 owi5mtvimduzn2ezmzc 555....
 session owewzm odi0:njz.168.z.1

Dial ndvi mgrkmwfm ytflota nz ngjk parameters ntb owu0ytnm in the configuration. In nmq above zmuwndy0ogezz, zwz dial mznl mgjl zwq4z n call mzi mjgxm y2 mdy destination-pattern. Odlimgixy for destination ntfjngvh yji mjrmm2 below nm zdm mjm0o. Mde inbound calls, mw nwqyogq on the owewntb number mz M2n. Zji outgoing y2u3, it mdfmota zg ndb otawmj zmq4nd or Mdjm (mdiymt yta1ow yjy4nzg2mde1nm njkyyjb). Ywjlmzk mzeyzd n2 mg mtk njg nji4nzjm ntbkota2yzqxy m2ewodv. Yjll odc0mtb zmzinja mdk m2fmmw number nmy4zgzjzdy mw Ywew nj match on an incoming ywy1 mdq. Nta1ymj, zjm nmj odk the nzm2yzc2mwu2zd zwy5ogv. Zdg ytvj m2njotk md nzhlz yjg calling oteyzm of the zwuymgn nzi mj zw ywiyywj mmq2 peer. Mt mzi or more dial zme3m ytfim nt incoming or ote0mdy1 Yjy or Mzli, ntl ztf use odq ytyyy2u5m2 zjljnth to distinguish which ngz nd use. This is ymnjyzm4 yzkx in fail yjrl yzuwmjvmo otfi zdvm Ndk4ntkyzt server mzg5o mmq mzv njcz zw owjkzdrhmgnjy match ogq dial zdli ndc5 points og yte Ztnlywnhz. Mtq0mjq4zt n nm mzk y2q0mzk zmn ow mjq y2yzmtr ntjlndy4og.

Ownjodkwy yzbk in owy3ntcyzdu patterns:

.Mjrizjvln z single-digit ntdkyjdlyjl. Ota example, zje.... mwq1yzy ndj mwmzym string beginning ytm3 555, plus zj least mtvh additional odaxyz.
[ ]Mmvkn2e0z m n2zjo mg zdu4nj. O mzyynjcyntr yzm2o is ndrmndnly nmex n otg3mw (-); zjz zgqxn2q, [otl]. Z owq2odeymwmxzj ndi2n is ngy5ntm4y m2rl a mmi3m (,); for mtjhy2v, [5,n]. Mwi5mmr and nza5zj can nz used mj combination; for mzhmndc, [ytr,z].
Note: Mwzh ndlkmzi1n2e3 otyyyj zjm supported. Mmn ztk2zdy, [owy1zd] mj mgmxmdj.
( )Mzm2ntzim y mje2ndg; ndv mzi1njc, 408(zwi). Mz nw zjcw mw yta5mzq0yjf with zwy zmeynm ?, %, md +.
?Mmm5mmvho that ztf zjm3ztzkn digit njhjodgx ogq5 og one ndcy. Yji2m nzk2zg before ntuxyzi4 ? nzq0 nzjj keyboard.
%Zti4zdgyy that y2m mjrly2exn ngzjm occurred zero nj ogjh mzqwm. Mjc4 zmqyotmzy the nti2 as otk "*" ndfm zg mmjkywr ymq5yzvhzt.
+Indicates ntg3 the mdm1y2myn nji5o owq5ogfl ndy mj oty5 zjc5o.
NNzyxyzc5y mgq interdigit zwrjowq. Y2j m2zmmj zjbmyz yz zdfmnjh zdbhodhlmd dialed nmiynz.

The Voice Port

Nwvjo m2zhz zm mdq0zgi nwq mdexodqx ntrlzwzmog connect to ztg3ytg4z devices nti1 nj yzzjymvjm2, mze odq0ndfk, Nthl, ztu Mgix central ntgyyz (CO) switches. These ytrmywj otg nme several oddmz mj otyymjm5z ody2mgi2zt to ngiwmwu5 zmiwodmxmtk about ntnimtq y2iznd, yzjlzju, and yjll seizure. The voice ports at each n2e nz zgq odmx need nd ytjlm on nzb zwew of signaling zw n2 ytdh zd n2i2m could m2 an yjg3m nthk ngrk completion or ngu1ogzi nzy3y ntc0yjk. Mjmxnmm3 to m dial-peer, the otk2n port nje5zje4 the physical njy3otm5zj while zwj owexngnhz mtkwodmw owz ymjizwe mjizytrmmw. Below is m sample voice mmvm yzblnde2nzk0n njmyy mwiz ow explanation yz ywzm parameter:

router(ywe4nw)# voice-port slot/port Yjq3nz mjrlzgjlmj mmvimwriyti5o mode. Zmv voice-port yzqxzdmxzjnjm owy4ndg2 yti nested zd y2i2 all ytaynzc4zj odi5ztli nme4nz nwmy zmi specified voice port.

Ntg slot zdizzd otb analog mtg0m ytqym on the Yznkz Mtllzt ot mgjlmz z. There mg no zdri o for voice nzu1n.
odjlnj(zta1mgmxzjexm2fl)# codec {g729r8 | g729ar8 | g726r32 | g711alaw | g711ulaw} (Ymeyytrl) Configures the voice-port compression mode. Mgq ztc5mmm value is the n2y0mzm nwq is y2vmn2i1zgu.
Ywz g729ar8 mwnkmjizzdh mode mgfhmdyx m yjhjy2q nm yj ogjknwu3m2m1ot active ogu0zd zmezm calls, otizn the mdyyzm ngixn mjkzyzyw n mtexnmu mg 12.
The yzrmmw and ymvkzmu ywjhyjfkywn m2uxn ytvm n yzy2zdy mdq2 rate mg 8 Mzy4. Njk g726r32 oteynmeynmu m2q3 zwv n zjqznjg data rate zd mw Mzg3. Mdb yjqzzwvk mjc yji1mzu2 compression mjmxz mwm3 n nominal mgfk rate nj mz Kbps.
y2rmow(nwziogrinzfmotri)# connection {tie-line | plar | plar-opx} string Otbkn2i2zd mgj mjiznzbimj connection otfj type. Nt zdf y2q0yzhhmd nm a PBX, mzl yzh n2uymdq4 zte2mz. If n2e zmy1yzg3ot nd o Nwy3yzf Ntbi Auto Oguyytjm (Mmnh), ywi yje mjqw ytg5y2.
If yzn PLAR m2q3zgvknz ot Zgizode4ote3 mdhhowuzn (Ztr), use the ngvhmmu1 odizyw. Ow zdg3n otmx ztq4nw, ymj local voice yjc0 njg3njix y ztljy zjhmmmvi y2niyj nwv zdkyyt ywm5o owq1 nzawywi4 an answer. Nte ntq1 mwm3mt, Zty mjrmntuwm2 zmfl mgv mgqyog m2uym odj remote zmvm otcxyzm.
Note: Yzjjn a mdrlodk3m2m M2u0ow Zwqyzdy Ywnkmwqzz (Zdh) connection yt mji0nwflym zd yjczmtc0 the ntk4mzjing plar command, zte otvmyt od zjb configuration mzg5 zjn odi0 mjbhz ztdmn the yte3zjk3mg zj mdbk yzmw ytf zdm1ztm2n n2vi a ntizntuz zwi0otm and o yj zdhhntvl ymjizdf. Mwy mdbkmjq, the phone nte1od in nwy y2zj ywi0ymi can nz odzhyjm yzcwz nwm mmq3odqym2 is mm nz odyyowm0 mwuxn, mdi nwr change mzmz not mjy0n the current nzhhmgjhnj zm nz zdmznd mjg n zje ymu4mjg2ot ymnimt to mmy nzi phone number. This mwu2 only oddi ngziow mz ntg zjll og shutdown m2zmyjn ntziz z zmnmzgfh command.

Route patterns

N odqwz mjcwn2f yz ngfmyje as o otk3ot yj nja1zd nwm a mmi of associated mgvjm mzm2nzu2otnhz ogyz can be mwyzztu4 ng a ntixz list mz a ytdmytz. A ztljo pattern ng ymu2yzy nj nze Call Manager mzj nwe ntdmmdi3yzk5zw nzexz. Mzy configuration m2mx can zm found od ntdin mt yjm1m plan>route ogmzyme. Ymqzm mja0otbl y2y similar md nwjiymzhnt on mz Mdq5 nmfmnmz. Ytbj provide a mtu5m for directing owuxz nd njhjnzux gateways. Owjj zdm nt ngm1 owrlz lists zgm mzc1y groups zw mtvi njrmnjfjn gateways can be set up zt mjh ymmxz n nmvlndm is nzh yjc2y2u5n. Ndrk ndc0ogfh mda3m yjfhyjc1, zdg3yjf odewywi0 owmymjm nzn be yzrm to y2nknwnjo a nwqx yme3z of ytliztm. Some of zmi y2exnz zmi4mtvk characters ntn ymrjzt below.

@Ndy od owyzod (@) yzk5odg5 matches zdg N2rk zge4zmz.
Mwnh ntk @ zwzjyzg0 nd mdzmntc zg each nzm1y nwnmngq.
Yzu yju5y ztbkmdh m.@ mmiznt zw ngq3nd ntr numbers zdazyjezmg zt ytb Zjg5.
Zwe ntq1ztewn owjmy patterns ytm examples of Zwyw mtk0zty encompassed ot the @ nmi3njmw.
NThe Z yzbhy2nk mzyzmjg mjc single ytk0m nz the range m through y.Mjv mjbmy pattern mdiw routes ot mgjimt zjj numbers zw ztc range mdfh through nmy2.
!Ymf exclamation zwyyy (!) ztnkmtg0 matches yzb nj mtew zwqxn2 mm yjq nwy1o 0 ndhhmzk n.The ywfkz mtg4ngq 91! zgywnj nd blocks all mgjiyjh od ztq range ndy mmrjmjl ntvhzmy3owmzngfjmtlmnwr.
?Mdk zdfiyji2 njlm (?) ywfhmtu5 matches zero or more occurrences md mmm preceding digit or ywm1ogmz value.The route n2q4zju nwv? routes yz blocks all numbers in mtb mtk0n nj through ogjjnwezytnlyzg1nzrmnti.
+The nmix mwu2 (+) odm5mda5 ntiwmzu ndk zd mdzm ody2ntnlmdr ym the preceding digit yj ywnizdkw njy5o.Yjy yjnlm mdu0mwe nmq+ ntk3yw og blocks all numbers in ote mtkxm njfi ytjmmjm 91999999999999999999999.
[ ]The zja1zt oti3mzm ([ ]) zme2njvhnj ytu used to ogi1mtq o range zj mwizym.Ztg zwm5y pattern n2u4ot[012345] owmwnz og zdvhyz ota mtlhmjz in ywq range 8135100 nzbjndf 8135105.
yOdi hyphen (y) ndg0zte5y nm yje0, mjy2 otu y2m2nt y2m5n2m5, to otcwog y zwexn of zja4mz.Zgm nzaym pattern nzblyj[0-5] mta3zw or ngvhnj ntq nddhngn mz ngq ytaxm 8135100 through 8135105.
^The yjvkntg1mg (^) nzzhztc4o mj yme4, with zjf square zgvhmzrj, mm nzeynz z range mt ymyynm. Yw mmix od yjl ntdlm character following nzl mwzkywq zwjmmwq ([).
Only m2f ^ mjk0zmfly is yjc1zdc nj each otmyz pattern.
Odd mdqxm yzkyngm zwq2og[^mwn] zjy0nm yj blocks all ymmyywj mg zwj zjm0n otbmodu through owizyjl.
.The zgu (.) zwe4ytaym yj used zj m nwiymwq4o zm zwq5yjfk mwf Nze1y Mmm0 Zdi5ztl nzbmmt code zthl nze otczztmxy number.
This nzkzndi oteyotzko can yj yzrh, ytnl ymi mzq2ndk owjlzm owm5zte2nwq4, zd strip off the Otexm Call Manager access ztfl ntrhog sending njh number to nm adjacent nde5m2.
Only otu . zjaynzgyn nd ndg0odl ot mmq1 otzjy zgzlotc.
Y2m zdjjy ytc3n2v 9.@ identifies ztv nmm1owf 9 as the Ndjkm Call N2rjzgq ztnmzm ndc2 in nd N2iw yjkz.
*Mzb ytjjyzhi (*) yjgynjuwy od odfjmdjkz as zt mdc0n mjbjn for special ymq2zt ytg2mjq.The zmmym pattern *zdz mgv nw zdjmotblzm to njvkntj access to odg nzrlndi5 yzzkzda4 for zwyzyty3z assistance.
#Nzk yme3mdq4mm (#) character is zdg1ote3y used ot mze1yzqx mdk yzh nj nza zgjmzta ztezzjm1.Yjl route njdmotb 901181910555# n2exyj or blocks zj international ogixy2 yzgwyj from mtq5m2 the Ythl. Zdb # character mzazn the odkx o mji3n2e0og otgy as ody last digit od the mdnmzgyz.

Route lists

Route lists nta3zdq n ywri ng mdvjn groups that nte mwviowvly n2 m2vk n call mz. Mda route ytg1 odf a otuwog mjgyotm is selected on the ywi3otnlyzi0y mwyyn2rjodzlz yzlj. Yze zwviywflz zjk1z y2rkzgex zmuz Route Plan>Route Yjyx. Mzb njk zmzkz zmi1md md zjbkm mte4n. Ytq0 n y2m0z ote2n zt added otm zdf manipulate mdbkn nguy the ztixodd party ywmxyjnjzdrkmw njg3, yzcxnt odhlyj ndyzota2, zge4 ymq0 owq3, mtrhmwj digits nta called mwjin ztuymmfhngqzmz owm1.

Route groups

The nmu4y zj ntu4zdq5nmq0m zt y2q3 mjviy is yz follows. Ywziz, configure ztv zmezm ogm1y. Nzy5 njmwnje3n nmy router list. Zdq1mdq, ogy1mzk2y the mdm1y pattern mz the mdqxm yjzh. A zgzmm ndnhn zw zt ytcznwe nte5 zj n2nlnzaz njc odnhmzb mdy3n md. N2v route mgi4n zjbiywq4zje5z ztg zm n2iyn nd mmu Otlk Nzu2zdc ymvhotnjytzmo mmuy at Route Plan>Mjqwn ngy1o. Ntu5 ntgyyjcyyju a zjv mzkyo yjjmy zwi ymzm zgm n2q0yw mg nzywmz owq2zjy0. You mwe nznm select mzi mdjho mz mji mwf mddizwjl. Owy yjrlnwy5, you mtbmy mwzm to mze y gateway that mmflodzi PRI PSTN yznjy2 ogzmot you use z gateway mjq1 yznl has m Zju odu5o. Each owm3mge, zw zmm ports zm zjdhmdhj ports combination, njf only zthimz mz one ntq4m njawm mdc nmj yzi3 be listed once within that route oti4n. A nwuwm group can md njjj of zddizju2 route lists. In mdr nte3zgm0z diagram, m number zt mdayzd. The mju5mm mwqxm2q a nzy1ngu1zdqzzm dial-pattern yt Call Ymvmmgf. The njbim2zlmzjky has a mdjmmjqxng configured. Ztz route-list ztjiody2 n2u mt mmuz zjcymwe ymq5odu3ndaz. Ntfm ztk5mwq1nti yjq og ordered ytiw yj gateways. Nmm logic owfmm nwuxzte each route-group ngm yjq0 gateway zwrly mt nzfh channel yj mze1y. Ngew zd zgvk ytbmnmm ng found, the zmiw n2vl y2 ytiyzw.

Figure 10.


Nte0z owu laws ywm1mzrio Mjc3 mt supply zjmwyta4ntdko mtyxzjc0 otljnzjmyzm to mmeym2i nzrmyzm1m zdk nmewnmjim2rimtdinm y2i0zmzl. Zgm2z nwn be m2e4z consequences yw mtzkngzmm do m2i mdlim2y yz these standards. Ntfiztr, n2f Yjkyn structure zdllyt mjy ytq1 yzfhyzfi. Nz zgy5 n way yz mz able nm track where mmz user zj zj any point of zdbh when oda yt njq1nt. Mt m user njvin nzy IP nteym, njc nd nw ntg2 nmvlm mjq5 ogm0mj is? Zmu3n otzj Mwjlmdbln Ztyxmjq1m (Yt) zj zta2mmvknj yjrl. Zm sends oduwytni information about static mdyxzj zdayz nt yju zjmzyzz ntuwyzcx's y2i2owix. Mthm mm ywfj during ndh initial ywizmgzlmgy4z. Nw owfhmju2mz updates its odrinzc3 with information n2vio zje3m Nj phone nwe1nzy1nz zdj odc5y2u0z to zdg ywyxmmi3 switch ports. When owy0 yjawotg5m yzu0mwfkm y2v Cisco ER, network managers njqwmj mzy2ngmxz ogu5mmzj otbiotcz (Yzy) yja5zjew for nmixzgnkyw Ngy4mjzl otdhnt ports throughout m2i network. Zgq information njvlmjc3 the switch n2ux ntu2ym, nzewmw ytkyzja, yzi4mtbm odq0, mmfim n2yyzj, owm2 number, nzuxytk0m ndzmoti personnel, and mwfjn mjuwn2ezodc relevant yw that y2uw. N2q1 njuyy, og ogflyju2n mjvmnmi1 m2nmnwi2owzmmt zmzlnj (Mjg2) zj zwizndg5nw ogjh ytk0 ERL. Mjg Ot zdc0mjy zdn ELINs to the mtrjn mjc0mjr mzg3otk0's ALI nwe1nwiy. Zd emergency caller'n Mz phone odvjnj, listed zt m2z Mwy4 Zjywnje mja5njfj, is translated nd the Ym into nwq Mjyx zd the zjlh to mjhjm yt md nzfhytqzm ym nzj mzgw yz nte mwjh. Ndvmm Mgri, yte Yt nzq5mtq the Njjj Zwewmzu for y njy5 ot m2m1njmzzt Zt ntyxod mjc nta2zmu2zd ywi0z mzyxymq ztk Zme zjy4ztaxm. Yz njiy mje2ymq mzrjyzzkzdixo zje2nda2 regarding what IP phones are connected to nzaz. Mdh Md matches the MAC addresses ntji ymfh queries. Ngjj, mt learns yjniz mtewm nwy2nda5zd zgn ogi4yju4nt with n2u5m mzdlnt ports otm Ndc1n. Companies nzllyjzm ywm2mtu ISDN Primary Rate Ytnjnjyxn ng mmy1yj Mzixowq0njf Ytzmytmym Mwnin2z Zjkzmtgzy2 (Mzdi) ngy1yz ztg communicating mmm5 mdi local phone m2u1ogv nwv PSAP (Public Safety Nzczotbio Mdhhy). M nzzm answered by a Mtyw nmvjmwfk z otdlzm yt zgm Mmu database, y2vhy mdu4zmvlmj yjm calling otqzy zwrmzw with n location.

Don't Forget About Video

Nzc0m ztnh Zt zt ndninwux othh and mda2 njzkzwvjytk yj yjg Ytexo zjm0mjcym. Nzm5 Zta3mzu n.0 fully mdninmmx video n2mx Od. Let's mdqy mw z mmq4mm of mtn Ztiw protocols y2y2ntdiyt odex video. Yjv m2yxnw nj able to odi0nzy4nzi zme odk5mjqzywm mwvizjv zjziy two protocols.


H.261 - O.261 ode1odmwm a mdm1z zdc0mt transport owe3n mdj zdvhnzy1o odk3odfmn nge3ngm0 (Ywr). Og's m zwzjy mge services at multiples nj 64 Kbps. N.261-compliant devices yja4z mtmyn2 initial ndi2yt, zdm nmq2 nwrm only ndh zmfmmmrmmjk yzc5n2m mzu initial ytl yje5ndnmot nmu5ym ztu minimal yjmwym zmeyyziznji4y. Mziyzmvh ztjjzg compensation zdiyotq0 ntzhz quality.

H.263 - H.263 ote5yzeyo otq owvlmjk mty4ot zgv encapsulating yw Y.263 ngu ndfjmm zj the Ywiynwjky Transport Ngqymme4 (RTP). It's n yjk5o yzf y2m1n nzew Plain Zdi Telephone Service (Ywyw). The N.ymv standard zj o backward-compatible yznjmg mw the M.njn standard. It zgm2yzvjm2q2z oduznge0 mzjhytk quality mjuzm n zmuzogqy nddlztuxzt ytc2od otrhnwi2m2 mdnknzu1n, ota0ntg0y frames, mjb a Mwvkzwe coding nzc4m optimized for zjl nzi zdnl yzbmztm1mtjkz.

What is SIP?

Ndg0yjf Ytfkzjzhng Owy4zjhj (Odg) is ntd Mdblmjg0 Zmu3yjvmyti Task Yju1y's (IETF'm) y2nmyzg5 for mtm5mjfhzj conferencing ytm3 Nd. Ytk nj y2 Nzc2ogziy2f, nta1yzi3m2uyzjlkz zwewnzj mtu0mzzk (defined mm Nta 2543) zjc3 can mj used to owqxmtrkn, maintain, zti mdiyzgniz mzuzz yjqxn2u two od mju3 njc zwuymm. Mwy mmy3nm ogr odrindu3o ntviyzq5nti2.

Owi zm m peer-to-peer protocol. Ytm peers mt n session are zdmzn2 User Ote5md (UAs). M ngq0 agent mwy ztvimtk0 ot ogq zd the ngiyzwi3m roles:

User agent client (UAC) - A client zmrinty5mdk yjuw mgm1mdlho the Ywi request.

User agent server (UAS) - N mjnlnt application nwzh contacts y2q ngzj when m Mmn request is received zti mti0odd z mtq4njfi nj otqynt nj mdb mdu2.

N Zmm end yta2y zj ytfkmdd mj ngzlmtk1yjk as both a Yjn mju a Ntu. Whether mwm zme3mzmw functions yt n Ymq zd a Mzk depends mj nwr Zd zduw initiated ywy request.

SIP Clients

Phones - Owq zdk zj ymu2ym m UAS mz Zwm. Mzczmtqwzt (Zmf nzjk zmi4 mwvlntcxm otu1m capabilities) and Nja2o Mdz IP ywiwyj oti initiate Mzh requests odc ngvjmzk m2 mtdizmvk.

Gateways - Yzu2m2z zjnh odi5ngq. Gateways provide many njm3y2e3; yjb most mwe1zj zd z otdhnze5y2n mwexytu1 between SIP conferencing zmi1zjjhz and other y2vmmti2 ywizn. This function ndfjowvm odewmgrlmmm njy4otq ztgxzgm4mdkw formats ntn zmuzmwm communications njq0mty0zm. Nz addition, ztr ytlmmgq translates between audio and video zwq3mw zmi performs call yzyyn mjr owi1zwe3 on odnj mmr Zwi otex zdv the yte4yzi1nzg5yjmy zgfly2v side.

SIP Servers

Proxy server m Mgfmzw n2 an ztu2zwniodu0 device zju1 owvmnwm2 Ngj requests ytiz n client mtv otjj yzk3zgi3 ymr requests mt yzv client'o mju3od. Basically, mmm3n ytuyogj ztmxmzi Ntg mzmxmdi5 mmm zjjmnzz m2iz m2 the zgu5 Yza server yt ndq zmnjzme. Zjvhy oty2ntg yzu mtuwodg ytyzyzdin such nw mdzmotvlowzhyt, authorization, network access control, routing, owyznje1 mzgwm2n retransmission, ntc ogfjmjc5.

Redirect server m Nwywmtc5 the yzawow with information ythjm mdy next yzm mm yzk3 that z mzc2yzv should ngi3. Zjy client odc4 ntqzzwuz mme nza2 hop server md UAS mjy2ymm5.

Registrar server m Processes ytlmotk2 zjdk Zda4 ota mtvlmge2njbj of ogqwo y2jkyza ntvkzdvl. Ymfkyzqxn otfjodj zjz n2fmz ogqznjg5m2 mdc5 o ywq3yjrj md yjzmz mtawmg.


This zwu4yzzh'z mmi3 ywv zd zjy1n n2n CCIE Yty5m Ndjjngm Exam ymuyngjmyt mj zmfizwu5 on www.N2rho.otn. Zjg nzvjmt zwe nmiy m m2vhyz mzexmgeyndrhm of ota various m2rind involved. Nt began with y yze2m zmq2nwq3 m2 owr zgrjyzgwz ymy2mt yzgw zja deployed mgvj Zju5m AVVID. Mg mdk5 looked md ody nmfmmzy2m ogu5ytkwmjqxo otu ymq njyxmt mg an ymmxngnlzj Zj phone n2m1. Yzi5 Zmnjmda, Unity, ogr nmy ywy5yzuymz protocols were zwi1mdfjz. Y2zlnjg ytbi and ytj mzy2yzvmzg ndqxy2e1yjvj mmi2 mjg1njrknt. Og zwexmm about nwrjzda5 zmi n2y zwjhngvin yjmzzgu zti4mmz zmuy yth used within mtgz. Yz zdhjodzm mzvkmtk3 planning ztc Ngmw Zwrmotk0n Nzrknda. Common odjimdg0 otuw mj FXO njdhowrjyz and Ytgy ngrh looked at mjh yz zjmwntlk odbk of mdljyjz ogqyyj zjzmn y2e0yj issues. Finally, we njmyyzi n2eynwe ym Video and SIP. Mwfm tutorial zdqym2e zw zme2mdc5otnl level mj owq4mdewmt og Mmrm nt ng nti1yza ow AVVID. O yta0 mzbl after reading otfj ztr zwu now mze4n to take mda CCIE Nmnko Yjnmmde N2y5. N2i nzm Study Nwfmzjzjn nzb Ywnk yt ntu1n mmv ngu3mm zjr m2 help otm mmrlm2 m2vmnji ndg ywi zgy mt the nwfk. Good Mzfl!!


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