[asterisk-users] Codec negotiation : expecting G726, getting G711a (alaw)

Jonas Kellens jonas.kellens at telenet.be
Thu Aug 5 02:27:08 CDT 2010

On 08/03/2010 04:21 PM, Philipp von Klitzing wrote:
> Also:
> There are at least two implementations of the g726 codec, i.e. g726 and
> g726aal2. For this also look at the g726nonstandard setting in sip.conf.
> It is quite possible that your problem is here.

I have the following setting in sip.conf :

g726nonstandard = no          ; If the peer negotiates G726-32 audio, 
use AAL2 packing
                                 ; order instead of RFC3551 packing 
order (this is required
                                 ; for Sipura and Grandstream ATAs, 
among others). This is
                                 ; contrary to the RFC3551 
specification, the peer _should_
                                 ; be negotiating AAL2-G726-32 instead

(so it uses RFC3551)

> For quick testing to see if the codec works at all: Configure your phones
> to do g726 only (so no alaw/ualaw at all).

Only when I configure my Grandstream to use only G726 (I have 8 
choices), I see that the g726-codec is used.
When I configure 7 x g726 and 1 x alaw, then again alaw is used !

Is it normal that Asterisk has such a great preference for alaw ?! The 
moment the peer suggests codec alaw (even if it is last choice), alaw is 
chosen by Asterisk for the communication.

Kind regards,


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