[asterisk-users] G729a and G729 interoperability

[Steve Underwood]

On 12/27/2010 08:05 PM, Elliot Murdock wrote:
> Hello!
>
> I am wondering how the differences between G729, G729a, and G729b
> effect call bridging and server interoperability.  For example, can
> one server use the G729 code with another server that uses the G729A
> codec?
>
> Also, which version is Asterisk set up to use?
>
> Thanks!
> Elliot
There is no compatibility issue between basic G.729 and G.729A. That is 
why they use the same SDP code. In practice it is rare to see a G.729 
codec in real world use. They are almost all G.729A. G.729 sounds 
better, but G.729A uses half the CPU power. Cheaper normally wins over 
better in the real world.

G.729 annex B is an add on, providing VAD features. It may be used with 
G.729 or G.729A. A separate entry in the SDP says whether this option is 
supported.

Steve