[asterisk-users] G.729 and Voicemail

[Gordon Henderson]

On Fri, 9 Oct 2009, Kevin P. Fleming wrote:

> Gordon Henderson wrote:
>> While we're on the subject of G.729...
>>
>> I can end to end use it with no transcoding, but voicemail is the main
>> sticking point for me - I'd need to transcode.
>>
>> So why can't voicemail store the audio in the format it's being streamed
>> in on?
>
> Why do you think it can't? It most certainly can, but only if that's the
> only format you will get connections in...

OK - You've got me there. I did try this once upon a time and it didn't 
work, and the config file (and wiki) seemed to imply that only the 3 
formats there were supported. Maybe I didn't try hard enough!

> if all your calls are G.729,
> just configure voicemail.conf to store in g729 format. If your calls are
> in a mixture of formats, then you'll have to use transcoding, but that's
> unavoidable (if the voicemail was left via a G.729 call and stored that
> way, but then later someone wants to listen to it using a G.711 call,
> then it will still have to be transcoded).

All deskphnoes I've ever bought support g729 natively. They also all 
support G711. The wholesale termination services I use all support g729 
too. The only fly in the oinkment is local PSTN connections which are 
obviously g711a. Now if voicemail would just blindly store in the incoming 
format, then that would be nice - VM files would be stored in g729 or 
g711, or whatever else comes in. It's just data afterall - why even think 
about transcoding? (Although I'm sure the answer will be something to do 
with trying to play g729, etc. attachments from an email or switching 
codecs mid-call from playing the prompts to playing the message)

It's all a bit bothersome - especially when dealing with weedy processors 
which barely manage a few GSM transcodes )-:

Gordon