call from CUCM to FXS voice router through CUBE problem

[ericlinji]

Hi

We met a problem in our testing environment:

<IP-Phone> -- <CUCM> -- <CUBE> -- <Voice Router(FXS)> -- Analog Phone

When we set the codec to g711, both call directions are ok.

When we set the codec to g729r8, call from analog to IP has no problem. But for the reverse direction,  the analog phone can ring but will be disconnected after several seconds. Before the call being disconnected, we find the codec is 'g729 pre-ietf' using the 'show call active voice brief' command on the CUBE.

Attached is the configuration of the CUBE and Voice Router(FXS). Really appreciate your advices.

Thanks!

Eric

[Dennis Mink]

Your XCODE resource on your cube is registered on your cucm through sccp. when you direct a call to your cube, from external, this XCODE is not available because the dial peer points straight to the VoiceGW with the FXS ports (see below). 

What you will need to do is point that dial peer to 192.168.0.115 not 10.101.10.25 thus sending it to CUCM. It will then invoke the XCODE resource in call manager, through the MRGL in the SIP trunks Device Pool.

dial-peer voice 8846111 voip
 destination-pattern 8846...
 session target ipv4:10.101.10.25
 dtmf-relay rtp-nte
 codec g729r8 bytes 40
 no vad   

[ericlinji]

Hi Dennis,

Thanks very much.

Due to other managment reason, our call flow must use the CUBE. And we don't have management privilege on the remote VoiceGW. Your suggestion seems doesn't applicable to our case.

Finally, we use the MTP on the CUCM and CUBE, and the call works both directions.

But do you have any other ideas?

Really appreciate your advices.

[Ayodeji Okanlawon · Accepted solution]

It looks like the analogue phone only supports g729 pre-itf format..

Unfortunately this codec format is no longer supported on any ios..

http://www.cisco.com/c/en/us/support/docs/voice/h323/14069-codec-complexity.html#pre_ietf

You can try your luck and see if this pre-itf is available on the ios, but I doubt it. You will need to have on all your dial-peers.

maui-vgw-01(config)#dial-peer voice 100 voip
maui-vgw-01(config-dial-peer)#codec g729r8 pre-ietf

The pre-ietf option in this command is not supported in Cisco IOS Release 12.2 and later.

[ericlinji]

Hi Ayodeji,

Yes, we noticed when the call fails, the codec in the router is g729r8 pre-ietf. But our IOS is 15.x and pre-12.2 can't be installed.

Is there any other solution for this except the MTP we tested successfully? We can't change the config of the remote VoiceGW router.

Best regards,

[Ayodeji Okanlawon]

Unfortunately, I don't see any other option. If the other router cant do standard IETF g729r8, then you are stuck with what you have now