Table Of Contents
Cisco 1751 Voice-over-IP Quick Start Guide
Installing WAN and Voice Interface Cards
If You Are Installing Voice Interface Cards
WIC and VIC Installation Procedure
Connecting the FXS, FXO, and E&M VICs to the Network
Connector Pinouts for FXS, FXO, and E&M VICs
Connecting the 2-Port ISDN BRI Card
Determining Voice Port Numbering
Cisco Router and Security Device Manager
Cisco IOS Command-Line Interface
Major Voice over IP Configuration Tasks
Information for International Users
Wildcards and Number Expansion
Checking Dial Peer Configuration
Checking E&M Interface Configuration
Tuning Parameters for Real-Time Voice Traffic
Configuring Frame Relay for VoIP
Obtaining Technical Assistance
Cisco Technical Support Website
Definitions of Service Request Severity
Obtaining Additional Publications and Information
Cisco 1751 Voice-over-IP Quick Start Guide
The Cisco 1751 Voice over IP Quick Start Guide explains how to install WAN Interface Cards and Voice Interface Cards, how to run configuration tools, and how to perform essential Voice-over-IP (VoIP) configuration tasks.
This document contains the following sections:
•
Installing WAN and Voice Interface Cards
•
•
•
Audience
This guide is intended primarily for users who configure and maintain routers, but are not necessarily familiar with tasks, the relationship between tasks, or the commands necessary to perform particular tasks to configure VoIP. We assume that you are familiar with Cisco IOS software, IP and telephony networks, and PBX operation for E&M installations.
List of Terms provides definitions for many of the technical terms used in this document.
Conventions
This document uses the following conventions:
•
•
•
•
•
•
Installing WAN and Voice Interface Cards
The Cisco 1751 router supports two slots that can be used to install either WAN Interface Cards (WICS) or Voice Interface Cards (VICS), and one slot that can be used to install only a VIC.
If You Are Installing Voice Interface Cards
The router supports one to three Cisco voice interface cards (VICs). Each VIC provides two ports. You need one VIC port for each voice connection.
Note
There are four types of VIC interfaces, as shown in Figure 3:
•
•
•
•
Figure 1 shows a typical VIC.
Figure 1 Voice Interface Card
You should install and cable VICs before performing the software configuration tasks explained later in this guide.
Warning
Caution
WIC and VIC Installation Procedure
Follow these steps, and refer to Figure 2 to insert a WIC or a VIC in the router:
Step 1
Step 2
You should be able to loosen the screws using your fingers; however, if the screws are very tight, you might need to use a Phillips screwdriver.
Step 3
Step 4
Step 5
Step 6
Figure 2 Inserting a WIC or VIC in the Router
If you need more detailed installation instructions, refer to the Cisco WAN Interface Cards Hardware Installation Guide.
Connecting the FXS, FXO, and E&M VICs to the Network
If you installed FXS, FXO, or E&M VICs, use the following cables, and refer to Figure 3 to connect them to the network:
•
•
•
Figure 3 Connecting VICs to the Network
When you are finished, reinstall any network interface cables you removed and turn on power to the router.
Connector Pinouts for FXS, FXO, and E&M VICs
Figure 4 shows the wiring patterns for FXS and FXO VIC connectors, and Table 1 lists the FXS and FXO pinouts.
Note
Figure 4 RJ-11 Wiring for FXS and FXO Connectors
Figure 5 shows the wiring pattern for an E&M connector, and Table 2 lists the E&M pinouts.
Note
Figure 5 RJ-48S Wiring for E&M Connectors
Checking FXS VIC Installation
If you installed an FXS VIC, connect a handset to the VIC port. When router power is on, you should be able to hear the dial tone when you lift the handset. The dial tone should stop after you dial a digit. If you have trouble, use the show voice port command to make sure that the VIC is installed correctly, or try connecting a different handset to the VIC.
2-Port ISDN BRI Card
The ISDN BRI NT/TE voice interface card provides a client-side (TE) ISDN S/T physical interface for connection to an NT1 terminating an ISDN telephone network. It can also be configured to provide a network termination (NT) interface with phantom power. Each of its two ports can carry two voice calls (one over each ISDN B channel), for a total of four calls per ISDN BRI card.
The card is illustrated in Figure 6.
Figure 6 2-Port ISDN BRI Card Front Panel
Connecting the 2-Port ISDN BRI Card
Use the straight-through RJ-45 cable to connect the 2-port ISDN BRI card to the ISDN network through a telephone wall outlet.
Caution
Step 1
Step 2
Figure 7 Connecting the 2-Port ISDN BRI Card
Note
Step 3
ISDN BRI Card LEDs
ISDN BRI voice interface cards have three LEDs, as listed in Table 4.
Table 4 ISDN BRI Voice Interface Card LEDs
B1
Call active on B1 channel
B2
Call active on B2 channel
OK
Interface is connected to an ISDN network
If you have additional cards to install, proceed to the appropriate sections in this manual. When you have finished all installations, see the Cisco 1751 Router Software Configuration Guide available on the Documentation CD-ROM.
Determining Voice Port Numbering
Enter the show voice port command to identify the port numbers of voice interfaces installed in your router:
Router# show voice port slot-number/portFigure 8 shows Cisco 1751 router slot numbering.
Figure 8 Cisco 1751 Router Slot Numbering
Figure 9 shows the VIC port numbering.
Figure 9 VIC Port Numbering
Example
If you install a VIC in both SLOT 0 and SLOT 1 of the router, the ports in each of these slots would be numbered as follows:
SLOT 0—0/0 and 0/1
SLOT 1—1/0 and 1/1
Cisco Router and Security Device Manager
Cisco Router and Security Device Manager (SDM) is a web-based configuration tool that allows you to configure LAN and WAN interfaces, routing, Network Address Translation (NAT), firewalls, VPNs, and other features on your router. If SDM is installed on your router, configure the router by following the instructions in the Cisco Router and Security Device Manager (SDM) Quick Start Guide. If this document was not shipped with your router, you can obtain SDM and instructions for installing it on your router from the following location:
To obtain the SDM release notes, and other SDM documentation, go to http://www.cisco.com/go/sdm and click the Technical Documentation link.
Note
Configuring Voice-over-IP
Voice-over-IP (VoIP) enables a Cisco 1751 router to carry voice traffic (for example, telephone calls and faxes) over an IP network, simultaneously with data traffic. (See Figure 10.) This guide describes the configuration tools and the major configuration tasks to configure the router.
Figure 10 Voice and Data Traffic on an IP Network
Configuration Tools
You can configure VoIP by using one of the following tools:
•
•
Cisco ConfigMaker Application
Use the Cisco ConfigMaker application to address and configure one or more devices or to create an entire network. A series of wizards and dialog boxes can make your voice-configuration task simple and fast.
Follow these steps to install the Cisco ConfigMaker application on your PC:
Step 1
Step 2
Step 3
Step 4
If the installer does not start after a few seconds, select Start>Run, and enter d:\setup where d is your CD-ROM drive.
Step 5
To learn about the Cisco ConfigMaker application, view the online movie, or use Cisco ConfigMaker Help Topics from the help menu.
You need administrative privileges to install the Cisco ConfigMaker application on Windows NT.
Cisco IOS Command-Line Interface
To configure your router from the command-line interface (CLI), refer to this guide, the Cisco 1700 Series Software Configuration Guide, or the Cisco 1751 Router Software Configuration Guide available on the Documentation CD-ROM.
Major Voice over IP Configuration Tasks
Follow these major steps to configure Voice over IP (VoIP) on your router:
Step 1
Step 2
•
The default voice-port values are usually adequate for both FXS and FXO voice ports. However, if you need to change the default values, refer to the Cisco 1751 Router Software Configuration Guide.
•
The default values for an E&M voice port are not sufficient to enable voice and data transmission over the IP network. E&M values must match those of the connected PBX device. Refer to the "Connecting the FXS, FXO, and E&M VICs to the Network" section.
•
The default values for a basic rate interface (BRI) port are not sufficient to enable voice and data transmission over the IP network. BRI values must match those of the connected PBX device. Refer to the "Connecting the FXS, FXO, and E&M VICs to the Network" section.
Step 3
Step 4
Step 5
Step 6
Information for International Users
International users must set the values of certain voice-port commands, like cptone, that are specific to their country. Refer to the Cisco 1751 Router Software Configuration Guide for details.
Entering Configuration Mode
You can configure your router for VoIP by entering commands at the CLI. This method of entering commands is called configuration mode.
Note
Follow these steps to enter configuration mode:
Step 1
To configure the router with a PC, the PC must have some type of terminal emulation software installed. The software should be configured with the following parameters: 9600 baud, 8 data bits, no parity, 1 stop bit.
Step 2
Step 3
Would you like to enter the initial configuration dialog? [yes]:Do not use the yes default. You need to enter no to enter the normal operating mode of the router.
Note
Step 4
Router> enablePassword:Configuration changes can be made only in enable mode. The prompt changes to the privileged EXEC (enable) prompt (Router#):
Router#Step 5
Router# config terminalRouter(config)#Step 6
Router(config)# ip routingRouter(config)# appletalk routingRouter(config)# ipx routingFor complete information about the global configuration commands and about configuring LAN and WAN interfaces on your router, refer to the Cisco IOS configuration guides and command references.
The rest of this guide explains how to configure your router for VoIP traffic.
Note
Note
Saving the Configuration
You must save the new configuration to nonvolatile RAM (NVRAM) periodically during the configuration process and also when you finish configuring the router.
Cisco IOS software uses two configuration files—startup config and running config. The startup-config file is a backup file that has all the information you specified about the router interfaces and is used by the router on the next restart. The running-config file has the current operating configuration with the changes you have just made. You can make any changes to the running-config file; however, these changes will be lost when the router powers down. To make these changes permanent, copy the running-config file to the startup-config file stored in NVRAM.
Follow these steps for each router to write the new configuration to NVRAM:
Step 1
Step 2
Router# show startup-config
Step 3
Router# show running-configStep 4
Router# copy running-config startup-configBuilding configuration. . .[OK]Router#The router is now configured to boot in the new configuration.
Dial Plan
Use a dial plan to map the destination telephone numbers with the voice ports on the router. In North America, the North American Numbering Plan (NANP) is used, which consists of an area code, an office code, and a station code. Area codes are assigned geographically, office codes are assigned to specific switches, and station codes identify a specific port on that switch. The format in North America is 1Nxx-Nxx-xxxx, with N = digits 2 through 9 and x = digits 0 through 9. Internationally, each country is assigned a one- to three-digit country code; the country's dialing plan follows the country code.
In corporate environments, VoIP can be configured to recognize extension numbers and expand them into their full E.164 dialed number by using two commands in tandem: destination-pattern and num-exp. Before you configure these two commands, map individual telephone extensions with their full E.164 dialed numbers. This can be done easily by creating a number expansion table.
For Cisco voice implementations, two types of dial peers are used to match a dialed number to either a local telephony port or a remote IP address:
•
West(config)# dial-peer voice 401 potsWest(config-dial-peer)# destination-pattern 14085553737West(config-dial-peer)# port 0/0The destination-pattern command defines the telephone number associated with the POTS dial peer. The port command associates the POTS dial peer with a specific logical dial interface, normally the voice port connecting your router to the local POTS network.
•
West(config)# dial-peer voice 501 voipWest(config-dial-peer)# destination-pattern 1919555....West(config-dial-peer)# session target ipv4:192.168.11.3The destination-pattern command defines the telephone number associated with the VoIP dial peer. The session target command specifies a destination IP address for the VoIP dial peer.
Use the dial-peer voice command to define dial peers and change to dial peer configuration mode. To see an example, refer to the individual sections on configuring FXS, FXO, and E&M interfaces later in this guide.
Wildcards and Number Expansion
Office PBXs are configured so that a user can dial a local call (within the same PBX) by dialing the extension only—for instance, the four-digit extension 3737 or the five-digit extension 53737 instead of the full telephone number, 1 408 555-3737.
You can provide the same shortcut on a VoIP network by using the number-expansion (num-exp) command.
East(config)# num-exp 5.... 1408555....This command tells the router to expand a particular sequence of dialed numbers into a complete telephone number (destination pattern) as shown in Table 5.
You can use a period (.) as a wildcard character representing a single digit in a telephone number.
You can use the show num-exp command to verify the number expansion information.
East# show num-exp [dialed-number]After you have configured dial peers and assigned destination patterns to them, you can use the show dialplan number command to see how a telephone number maps to a dial peer.
East# show dialplan number [dialed-number]
Note
Configuring FXS Interfaces
This section explains how to configure ports on FXS VICs that connect directly to a standard telephone, fax machine, or similar device.
Figure 11 shows a basic voice network. A small business uses a Cisco 1751 router (named West) to provide telephone and fax connections among employees in its office. Two of these telephones are connected to an FXS VIC port in the West router.
Figure 11 Basic Voice Network (West Router)
Note
(For information about port numbering, refer to the section on "Determining Voice Port Numbering" earlier in this guide.)
Table 6 West Router Telephone Numbers and Voice Ports
408 555-3737
0/0
408 555-4141
0/1
Note
Local Dial Peers
To route a received voice call to the right destination, the router needs to know which telephone number belongs to each voice port. For instance, if a call comes in for 408 555-3737, the router needs to know that this telephone is connected to voice port 0/0 (as shown in Figure 11.) In other words, the router needs to know the information in Table 6.
To hold this information, Cisco IOS software uses objects called dial peers. A telephone number, a voice port, and other call parameters are tied together by associating them all with the same dial peer. Configuring dial peers is similar to configuring static IP routes—you are telling the router what path to follow to route the call. All voice technologies use dial peers to define the characteristics associated with a call leg. A call leg is a segment of a call path, for instance, between a telephone and a router, a router and a network, a router and a PBX, or a router and the PSTN. Each call leg corresponds to a dial peer.
Dial peers are identified by numbers, but they are usually referred to as tags to avoid confusion with telephone numbers. Dial-peer tags are arbitrary integers that can range from 1 to 231-1(2147483647). Within the allowed range, you can choose any dial-peer tag that is convenient or makes sense to you. Dial peers on the same router must have unique tags, but you can reuse the tags on other routers.
Table 7 assigns a dial-peer tag to each telephone number and its associated voice port on the West router. This type of dial peer is called a POTS dial peer or a local dial peer. The term "POTS" (plain old telephone service) means that the dial peer associates a physical voice port with a local telephone device.
Table 7 West Router Local Dial Peers
408 555-3737
0/0
401
408 555-4141
0/1
402
You should construct a table similar to Table 7 for your own routers, assigning your own telephone numbers and dial-peer tags.
Note
To configure the router with the dial-peer information in Table 7, enter the following global configuration commands:
West> enablePassword:West# configure terminalWest(config)# dial-peer voice 401 potsWest(config-dial-peer)# destination-pattern 14085553737West(config-dial-peer)# port 0/0West(config)# dial-peer voice 402 potsWest(config-dial-peer)# destination-pattern 14085554141West(config-dial-peer)# port 0/1West(config-dial-peer)# exitWest(config)#These commands are summarized in Figure 12.
Figure 12 West Router Configured for Local Dial Peers
The dial-peer command always takes the argument voice. The number following it is the dial-peer tag, and pots is the type of dial peer.
Cisco IOS software refers to a telephone number as a destination pattern because it is the destination for an incoming or outgoing call. Enter these numbers with the destination-pattern command. A destination pattern can include asterisks (*) and pound signs (#) from the telephone keypad, and commas (,) and periods (.), which have special meanings. Parentheses ( () ), hyphens (-), slashes (/), and spaces ( ), which are often used to make telephone numbers easier for humans to read, are not allowed.
Notice that the commands in the examples puts the prefix 1 (used in the United States to indicate a long-distance number) and an area code in front of the remaining numbers to complete the destination pattern. You need to include similar codes for your country if the VoIP equipment needs to establish a connection to the PSTN.
Note
The business that owns the West router also has a branch office in the East. Figure 13 shows the East office network, and Table 8 lists the phone numbers, voice ports, and dial-peer tags for this office.
Figure 13 Basic Voice Network (East Router)
Table 8 East Router Local Dial Peers
919 555-8282
19195558282
1/0
901
919 555-9595
19195559595
1/1
902
Enter the following commands to configure the local ports on the East Router with the dial-peer information in Table 8:
East(config)# dial-peer voice 901 potsEast(config-dial-peer)# destination-pattern 19195558282East(config-dial-peer)# port 1/0East(config)# dial-peer voice 902 potsEast(config-dial-peer)# destination-pattern 19195559595East(config-dial-peer)# port 1/1East(config-dial-peer)# exitEast(config)#These commands are summarized in Figure 14.
Figure 14 East Router Configured for Local Dial Peers
Checking Dial Peer Configuration
If you configured POTS dial peers on your router by following these examples, you can place calls between telephones connected to the same router. You can also use the show dial-peer voice command to verify that the data you configured is correct.
Note
Calling Between Routers
To enable the West and East offices to send voice traffic to each other over the same IP network they use for data traffic, use a WIC on each router to provide a connection to the IP network, as shown in Figure 15.
Figure 15 IP Connection Between Routers
Look at the connection between the West router and the IP network. This connection does not include a voice port or an attached telephone—it leads from a WAN interface to a remote destination somewhere on the IP network. IP routers know how to locate IP addresses on the network, but they do not know how to locate telephone numbers. To route an outgoing voice call over this connection, the West router has to associate a telephone number in the East office with the IP address of the East router.
Table 9 assigns a dial-peer tag to each telephone number and its associated IP address on the West router. This type of dial peer is called a remote dial peer or VoIP dial peer. (Remember, the dial-peer tags are arbitrary.) The term VoIP means that the dial peer associates a telephone number with an IP address.
Create a VoIP dial peer on the West router for every telephone on the East router, all associated with the same IP address. But it is much easier to use periods as wildcards, as shown in Table 10.
Table 10 West Router Remote Dial Peers with Wildcards
East
919 555-xxxx
1919555....
192.168.11.3
501
Construct a table similar to Table 10 for your own routers, assigning your own telephone numbers,
IP addresses, and dial-peer tags.
Note
Enter the following information on the West router to create the dial-peer configuration given in Table 10:
West(config)# dial-peer voice 501 voipWest(config-dial-peer)# destination-pattern 1919555....West(config-dial-peer)# session target ipv4:192.168.11.3Cisco IOS software describes the remote network as the session target. This command is followed by the IP address of the remote router. The prefix ipv4 means IP version 4. Alternatively, you can use the prefix dns followed by the Domain Name System (DNS) name as follows:
West(config-dial-peer)# session target dns:voice.eastrouter.comConfigure a dial peer on each router for each telephone number on every other router connected to it.
Make things easier by configuring number expansion for East router telephone numbers on the West router:
West(config)# num-exp 5.... 1919555....Now users can dial a five-digit extension beginning with 5 from a telephone on the West router to reach a telephone on the East router.
These commands are summarized in Figure 16.
Figure 16 West Router Configured for Remote Dial Peers
The West router is now configured to send calls to the East router.
Table 11 shows how to configure the East router to send calls to the West router.
Table 11 East Router Remote Dial Peers with Wildcards
West
408 555-xxxx
192.168.19.27
801
Enter the following information on the East router to create the dial-peer configuration given in Table 11:
East(config)# num-exp 5.... 1408555....East(config)# dial-peer voice 801 voipEast(config-dial-peer)# destination-pattern 1408555....East(config-dial-peer)# session target ipv4:192.168.19.27These commands are summarized in Figure 17.
Figure 17 East Router Configured for Remote Dial Peers
Other Routers on the Network
If the path between endpoints of a voice call travels through intermediate routers, configure those routers for VoIP traffic, as described in the section "Configuring FXS Interfaces" earlier in this guide.
You need to configure POTS or VoIP dial peers on an intermediate router only if that router also has voice devices attached to it.
Checking FXS Configuration
If you configured VoIP dial peers on your router by following these examples, you can place calls from that router to telephones on the remote routers (using just the extension if you configured number expansion). If you have trouble placing calls, ping the remote router to make sure you have IP connectivity, or use the show dial-peer voice command to verify that the data you configured is correct.
Note
Configuring FXO Interfaces
FXO interfaces provide a gateway from the VoIP network to the analog PSTN or to a PBX that does not support E&M signaling so that users can reach telephones and fax machines outside the VoIP network. Figure 18 shows a typical FXO gateway attached to the West router.
Figure 18 FXO Gateway to PSTN
To create a POTS dial peer for an FXS interface as explained earlier, you enter the complete telephone number of the attached telephone as the destination pattern for incoming calls. However, to create a POTS dial peer for an FXO interface, the destination pattern refers to outgoing calls, and you can include wildcards in it because the PSTN performs the switching.
The VoIP feature can also remove digits that you do not want to send to the PSTN. For instance, to dial 9 to reach an outside line (that is, the analog PSTN), enter the following commands:
West> enablePassword:West# configure terminalWest(config)# dial-peer voice 201 potsWest(config-dial-peer)# destination-pattern 9West(config-dial-peer)# port 0/0When you dial 9, the router makes a connection to the PSTN through voice port 0/0. The PSTN then provides a dial tone, and any digits you enter on the telephone thereafter are interpreted on the PSTN.
To enable East router users to make calls over the West router local PSTN, enter the following commands:
East(config)# dial-peer voice 701 voipEast(config-dial-peer)# destination-pattern 7East(config-dial-peer)# session target ipv4:192.168.19.27West(config)# dial-peer voice 601 potsWest(config-dial-peer)# destination-pattern 7West(config-dial-peer)# port 0/0When you dial 7 on the East router, the call is connected to the PSTN on the West router. The PSTN then provides a dial tone, and any digits you enter on the telephone thereafter are interpreted on the PSTN.
Note
Checking FXO Configuration
If you configured your FXO interface according to this example, you can place outgoing calls over the PSTN. If you have trouble placing calls, use the show voice port command to make sure that the VIC is installed correctly. Use the show dial-peer voice command to make sure that the data you configured is correct, and test the PSTN by connecting a handset directly to the PSTN outlet and placing a call.
Note
Configuring E&M Interfaces
If you have more than a few voice users at each location, the cost of voice ports and routers and the effort needed to configure dial peers for all the combinations of origins and destinations increases rapidly. In this situation, it might be more efficient to use a PBX at each location to switch local traffic and direct incoming calls and then use E&M VICs to connect the PBXs over an IP network.
Figure 19 shows a company with two offices, West and East. Each office has a PBX to operate its internal telephone network, and the IP network carries voice traffic between the offices. Each PBX connects to an E&M VIC port in the router.
Figure 19 Linking PBXs over the IP Network (Local Dial Peers)
To configure E&M voice ports, you need to use the following commands beginning in privileged EXEC mode:
Both PBXs in this example use E&M interface Type 2, with four-wire operation and immediate-start signaling. The values for your configuration depend on your PBX and are available from your telecommunications department or the PBX manufacturer. For more information about E&M interface configuration commands, refer to the "VoIP Commands" chapter of the Cisco 1751 Router Software Configuration Guide.
In this example, West users can dial 5 and a four-digit extension to reach telephones in the East Office. East users can dial 5 and a four-digit extension to reach telephones in the West office.
The West router connects to the PBX through an E&M VIC port 0/0. This port is associated with a POTS dial peer for incoming calls. But you no longer need to associate every telephone number with its own port. Instead, you can configure a local dial peer as if all the West telephones (represented by a wildcard destination pattern) are connected directly to this port, as shown in the following commands:
West> enablePassword:West# configure terminalWest(config)# dial-peer voice 111 potsWest(config-dial-peer)# destination-pattern 1408555....West(config-dial-peer)# port 0/0Configure VoIP dial peers for outgoing calls and associate destination phone numbers on the East router with that router IP address, as shown in Figure 20, and in the following commands:
West(config)# dial-peer voice 121 voipWest(config-dial-peer)# destination-pattern 1919555....West(config-dial-peer)# session target ipv4:192.168.11.3West(config-dial-peer)# exitWest(config)#Figure 20 Linking PBXs over the IP Network (Remote Dial Peers)
Now configure number expansion so that numbers beginning with 5 (belonging to the East office) and sent by the West PBX to the West router are expanded into the full destination pattern:
West(config)# num-exp 5.... 1919555....
Note
Finally, enter the following global configuration voice-port command to configure the E&M port:
West(config)# voice-port 0/0West(config-voice-port)# signal immediateWest(config-voice-port)# operation 4-wireWest(config-voice-port)# type 2
Note
Note
Configure the East router similar to the West router. The East router connects to the PBX through an E&M VIC port 0/1. Enter the following commands to configure a POTS dial peer for all East telephones:
East(config)# dial-peer voice 211 potsEast(config-dial-peer)# destination-pattern 1919555....East(config-dial-peer)# port 0/1Enter the following commands to configure a VoIP dial peer for telephones on the West router:
East(config)# dial-peer voice 221 voipEast(config-dial-peer)# destination-pattern 1408555....East(config-dial-peer)# session target ipv4:192.168.19.27East(config-dial-peer)# exitEast(config)#Enter the following commands to configure number expansion and to make it easy for East users to dial numbers on the West router:
West(config)# num-exp 5.... 1408555....Finally, configure the E&M port:
East(config)# voice-port 0/1East(config-voice-port)# signal immediateEast(config-voice-port)# operation 4-wireEast(config-voice-port)# type 2Checking E&M Interface Configuration
If you configured the E&M interfaces correctly, you can place calls from a telephone served by one PBX to a telephone served by the other PBX (using just the extension, if you configured number expansion). If you have trouble placing calls, ping the remote router to make sure you have IP connectivity.
Note
Tuning Parameters for Real-Time Voice Traffic
Voice traffic is much more sensitive to timing variations than data traffic. For good voice performance, you need to configure your data network so that voice packets are not lost or delayed. To achieve the level of network performance needed for VoIP connections, use the following features to improve quality of service (QoS):
•
•
•
•
Cisco IOS software provides many other tools for ensuring QoS, such as custom queuing, priority queuing, and weighted fair queuing. For further information and more detailed examples of QoS configuration, refer to the Cisco 1751 Router Software Configuration Guide.
Note
Configuring VoIP on a Frame Relay link involves special considerations. These are discussed in the section "Configuring Frame Relay for VoIP."
Need for Quality of Service
On a relatively low-bandwidth connection, such as a PPP or High-Level Data Link Control (HDLC) serial link, you should consider using methods to ensure QoS. If you have a high-bandwidth network, such as Ethernet or Fast Ethernet, and voice and data traffic together occupy only a small fraction of the bandwidth available, you might not need to provide QoS. (See Figure 21.)
Figure 21 Bandwidth v. Quality of Service
IP Precedence
Use the ip precedence command to give voice packets a higher priority over other IP data traffic. Every IP packet is given a precedence level. In IP precedence, the numbers 1 through 5 identify classes for IP flows; the numbers 6 through 7 are used for network and backbone routing and updates. You can configure voice packets for higher priority by setting the IP precedence value to 5. Internal routers using weighted fair queuing will give these packets prio
Guest
