Thanks, we have been going through this document and have not hit it yet. It does not seem to matter where the calls come from, if it is G729 to Unity it is garbled. For example, if a G729 user records their greeting, it is garbled as well.

Thanks for the response. The problem is PSTN and IP phone, if they use G729. Everything is fine when PSTN and IP Phone use G711. We had already changed the Wideband parameter when we deployed this version of Callmanager.

Id say since the codec is being changed at the CUCM, and other G729 calls are not affected, there seems to be something in the CUC. Is this a new problem?

This CUC deployment is about 9 months old but we only recently started deploying remote sites with G729 and that is when we started seeing the issues. Before that everything was G711 so we were fine.

Take a local phone and change the region to a remote region to use 729. This will eliminate all gateway and wan issues and put the problem squarely in Unity's lap. As Unity does the transcoding natively, did you see this problem after several conversions to 729 or right away no matter how many folks were using that codec?

Another suggestion, depending on how far you want to go with this, is to put the vm ports in a vm region and use only 711 to that region. usage on your wan would depend on how many concurrent vm you think you might have or are you saying you get garbled local phone to remote phone or remote pstn to local phone too?

I have adjusted so the phone is talking G729 directly to Unity and I still get the garbling. I will use your tip for the seperate Region workaround if I have to. Thanks for that tip.

I just changed the recording format on Unity from G729a to G711mu-law. Even though this is the recording format only and still G729 stream to Unity, it seems to be improving things. I just wonder what the storage impace will be if I leave it on G711mu-law. I also have a TAC case open and am awaiting feedback.

Thanks Jason

I would not store in 729 unless that is the majority of your users. Shouldn't have a major impact on storage.

I had a similar problem with CUCM 6.1 CUC 7.0(2) where where calls came in via an H323 trunk running G729. I had set the recording codec to G729a and the customer complained of poor audio quality with voicemail messages. It seems looking at a design guide for unity connections, the way things work is that every G729 call is transcoded to PCM linear then encoded to G729a:

g729->PCM->PCM (apply AGC)->g729a

Since all calls are converted to 16 bit PCM even if the recording and line codec are the same,and since g729 is a lossy codec, each transcode will decrease the quality. I assume this is having an adverse effect. I too have changed the recording format to G711 and have seen an improvement.

Rgds,

Lolu