Cisco IOS Dial-Peers: VoIP Dial Peers

In the last blog, an inbound POTS dial-peer was created for Global Knowledge. When purchasing the circuit, we requested only the last 5 digits of the direct inward dialing (DID) block of numbers. For the sake of our example, we will assume Global Knowledge purchased the following DID block from the PSTN provider: • (212) 551-1000 through (212) 551-1999 Since we will only be receiving the last 5 digits from the carrier, we will be receiving the following range of digits from the provider: • 11000 - 11999 The received digits (called party number) can be verified with the “debug isdn q931” command on the Cisco router. Assuming that you have a telnet or SSH session to the router, remember to turn on terminal monitor from a privileged EXEC Cisco IOS prompt as shown below: Router# terminal monitor The terminal monitor command cannot be executed from configuration mode (unless the do command shortcut is used). The terminal monitor command redirects console output to the virtual terminal session (vty ports) on the Cisco router. The debug isdn q931 is a great way to verify the calling party and called party number information sent in the Q.931 setup message from the provider. The debug isdn q931 command is useless with analog FXO or analog trunk (DID) ports. The “debug voice ccapi inout” command is much more useful when analyzing calls over analog circuits. T1 CAS circuits are by far the hardest circuits to troubleshoot. It is recommended to use both the “debug vpm all” and the “debug vpm signal” commands when troubleshooting issues on channel associated signaling (CAS) voice interfaces. The inbound dial-peer for calls from the PSTN is the POTS dial-peer 1 that was created in the last blog. Two outbound VoIP dial-peers will be created to route the outbound call leg. Analyze inbound and outbound dial peers from the router’s perspective. If I was a router… and I was receiving a call from a PRI… and then forwarding the call to Call Manager (CUCM), what dial-peer elements would I need to achieve this? The following dial-peer examples are the two VoIP dial-peers used to route the last 5 digits to two different Cisco Unified Communications Manger servers performing call processing: Dial-peer voice 100 voip Destination-pattern 11… Ip qos dscp cs3 signaling Dtmf-relay h245-alphanumeric No vad Codec g711ulaw Preference 1 Session target ipv4:10.1.1.1 Dial-peer voice 101 voip Destination-pattern 11… Ip qos dscp cs3 signaling Dtmf-relay h245-alphanumeric No vad Codec g711ulaw Preference 2 Session target ipv4: 10.1.1.2 In the next blog, we will discuss all of the commands provisioned in the previous dial-peers. There are many other optional commands to include in the configuration of H.323 gateways and H.323 dial peers. REFERENCES Global Knowledge Cisco Unified Communications classes www.globalknowledge.com/go/cisco Cisco Press Books – CVOICE / GWGK / TUC www.ciscopress.com Dial Peer Configuration on Voice Gateway Routers (12.4T) http://www.cisco.com/en/US/docs/ios/voice/dialpeer/configuration/guide/12_4t/vd_12_4t_book.html Cisco IOS H.323 Configuration Guide (12.4T) http://www.cisco.com/en/US/docs/ios/voice/h323/configuration/guide/12_4t/vh_12_4t_book.html