transcoding between cucm and ccme

[nicanor00]

Hi

I have cucm 8 with router 2900 voice gateway on central site and CCME on 6 remote site (let say site A,B,C,D,E,F)

I need to reduce voice call bandwidth between some site

Now I use G711 for all call

see below what  I plan to do

- Use G729  for call between cucm and ccme site (A,B,C,D)  and between ccme site (A,B,C,D)

- Internal call on each site (central site and site A,B,C,D,E,F)  will use G711 as now

- Call going and comming from site E and F to all other site (central site and site A,B,C,D) use G711 as now

I see many case about transcoding but I dont uderstand how to implement it

I am new on this type of configuration

I already installed PVDM card on voice gateway and CCME

Please help

[Aaron Harrison]

Hi

Basically you need a transcoder where you have a requirement to run G729 over the WAN, to a device that does not support g729.

What this means in practice is that if you want to make a call from an IP Phone to and IP Phone, you do not need a transcoder - the phones support G729 natively.

If you want to make a call from a gateawy to an IP Phone using G729, you do not need a transcoder. The gateway will use more DSP, so you should have more DSP capacity than PSTN channels (e.g. if you have a remote site with a T1, a PVDM-32 would allow a good number of calls to route over the WAN). The phone supports g729 just fine.

If you want to make a call from a remote gateway or IP Phone, to (for example) a voicemail server at your CUCM site that does not support G729, then you need a transcoder. The transcoder would need to be at the CUCM site, and the media from the call woudl route via the transcoder which would decode the g729 and send it on to the voicemail server as G711.

Other examples of services that may not support G729 are the CUCM conference bridge, or UCCX.

So you need to determine what endpoints you have on each site, and whether they support G729 natively.

Aaron

[nicanor00]

There is not voice mail on my cucm

I dont need transcoding over PSTN

I need transcoding only for ip phone to ip phone call on the IP wan between some site

I use ip phone : 7962, 7942, 6921, 7911

- Use G729  for call between cucm IP phone and ccme ip phone site (A,B,C,D)  and between ccme site (A,B,C,D)

- Internal ip phone call on each site (central site and site A,B,C,D,E,F)  will use G711 as now

- ip phone Call going and comming from site E and F to all other site (central site and site A,B,C,D) use G711 as now

How can I configure it ?

[Aaron Harrison]

Hi

Quote myself:

What this means in practice is that if you want to make a call from an IP Phone to and IP Phone, you do not need a transcoder - the phones support G729 natively.

If you are only concerned about compressing calls from IP phone to IP Phone, then you just need to ensure that you configure:

- CUCM so that the remote sites on CME (i.e. the gateways) are in a region that specifies G729 to other regions

- CUCM so that calls between CUCM sites have regions that specify G729 between them

- CME so that dial-peers pointing to remote sites permit G729

Regards

Aaron

[nicanor00]

Hi and tnaks for you answer

If I understand well

All configuration are made in the voice gateway and the CME, nothing is done in the CUCM

Please do you have any documentation example that show step by step  configuration ?

[nicanor00]

Hi

Please somebody can help ?

Thanks