Default Codec for Voip Dial-Peer: G729

I didn’t know that! The default codec used by the voip dial-peers is G.729, I got the proof when I was calling from a PSTN phone towards H.323 branch router over T1 and passing it to central CUCM over voip. And also this was the reason I was not getting MoH at PSTN because MoH stream was multicasting over G711 only! Though my H.323 gateway and the destination phone was located on the same region but the call was establishing over G729. Then I found the issue after seeing the result of the command ‘sh voice call summary’:

Branch#sh voice call summary
PORT           CODEC     VAD VTSP STATE            VPM STATE
============== ========= === ==================== ======================
0/0/0:23.1      g729r8 n  S_CONNECT             S_TSP_CONNECT’

I was so surprised!! It’s the root cause my MoH is not working!!! I just asked one of my friend (Olivier: http://ccievoice.ksiazek.be) about the issue, he smiled and told me it’s normal to use g729 by default for the dial-peers unless I change from the voip dial-peer towards CUCM. Hats of my friend! I just changed the codec to G711 and it’s was working like magic.

!
dial-peer voice 9 pots
translation-profile incoming PstnInStripTo4
incoming called-number .
direct-inward-dial
!
dial-peer voice 90 voip
destination-pattern 3…
session target ipv4:10.10.10.11 ! CUCM IP
codec g711ulaw
no vad
!

After configuring that:

SB#sh voice call summary

PORT           CODEC     VAD VTSP STATE            VPM STATE

============== ========= === ==================== ======================

0/0/0:23.1      g711ulaw n  S_CONNECT             S_TSP_CONNECT

0/0/0:23.2      –          –  –

And my MoH issue is fixed! It was a good learning for me. 🙂

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