[Asterisk-Users] VAD/DTX implementation through zaptel cards

[Steve Underwood]

Steve Kann wrote:

> Eric Wieling wrote:
>
>> parijat at varaha.com wrote:
>>
>>> Hi,
>>> How can i implement VAD/DTX using zaptel with asterisk towards PSTN. 
>>
>>
>>
>> TDM (PSTN/telcos) do not support VAD. The entire idea of VAD is not 
>> even a valid idea.
>
>
> Doing VAD on audio coming _from_ the TDM world certainly is something 
> you might want to do, to dramatically reduce the bandwidth you consume 
> when sending the audio via VoIP channels.
>
> This kind of thing is not presently implemented in *, though, but it 
> could be. (note: doing it well will require a bunch of CPU, though. I 
> wonder if it could be done in the same DSP that is doing 
> echo-cancellation on the new TE4xxP boards?

Unless Digium's plans changed since the last time I spoke to Mark, the 
answer would be no. I believe they are using a dedicated function echo 
canceller device.

Regards,
Steve