Transcoding without a CME or CUBE Deployment

[skten-auy]

Evening all,

Where a voice gateway is being used to handle SIP-SIP calls without Call Manager or CUBE in the environment, what (if any) is the correct way to configure transcoding?

With a dspfarm configured, we are finding that DSP's are being allocated for all calls even if codec and packetization are consistent on both call legs. Is it correct that this is occuring because there is no CUBE deployment?

Thanks in advance.

[Chris Deren]

If there is no CUCM or CME what is your call processor?  

Chris

[Anthony Holloway]

This person could be using a Cisco voice gateway to terminate a SIP service from their ITSP and handing off to a SIP enabled PBX such as Avaya.

ITSP <---SIP---> Cisco VG <---SIP---> Avaya

Maybe.

[Ayodeji Okanlawon]

In addition to Chris's question, what is the call flow? Can you describe this to us? Where is the gateway sending the calls to?

[skten-auy]

Anthony was spot on, the VG is to provide demarcation between the ITSP and a SIP PBX, the SIP PBX can not talk directly to the ITSP for topology reasons.

ITSP <--SIP--> VG <--SIP--> PBX

Transcoding aside the box has to do very little so wanted to avoid having to license CUBE.

If CUBE is required, I would have assumed that without it, calls that required transcoding would simply fail (Which we see if there is no dspfarm configured), however with a dspfarm configured we are finding that a DSP is allocated to every call regardless, which is why I'm a little confused and thought perhaps it was a configuration issue.

Thanks.

[Ayodeji Okanlawon]

First of all in this topology, you need a CUBE license. There is no way around it. Your gateway is processing two voip legs, providing demarcation between the outside and your PBX, hence its acting as a CUBE.

Second, we will need to look at the sip traces and your configuration to know why xcoder is been invoked.

[skten-auy]

I do not believe CUBE licensing is required if telephony-service is not configured. Correct me if I'm wrong.

We can easily acheive want we want (without transcoding) without configuring telephony-service.

What we are finding is that the moment a dspfarm is configured, without telephony-service, a DSP is immediatly allocated on all calls. This is why we questioned if you can actually transcode without CUBE.

I suspect I have my answer (Unfortunatly, no), but will come back with some debugs shortly as it is interesting that we are seeing what we are.

[Anthony Holloway]

As far as I am aware, you will have to use CUBE/Telephony Service on the IOS gateway in order to register the internal DSP's as transcoding resources for use by your voice gateway.

http://www.cisco.com/c/en/us/support/docs/voice-unified-communications/unified-border-element/100480-cube-transcode.html#full_config

In other words, I don't think you can use internal transcoders in your scenario without the telephony-service command.