[Asterisk-Users] codecs

[Martin Pycko]

Well this feature only works in a scenario that
a SIP phone places a call to asterisk ...
and then asterisk responds with SIP_CODEC codec to the phone's
INVITE message.
It does not allow changing the codec for outgoing calls placed
from asterisk.

Anyways "codec preferance" feature was added for the purpose that
you're talking about.

once you place
dissallow=all
and
allow=alaw
allow=gsm

in sip.conf then when asterisk is placing a SIP call it'll present
to remote party that it prefers first alaw, then gsm, etc. codec.
And if the remote SIP device supports the first codec it should
respond in this codec.

regards
Martin

On 24 Feb 2003, William X Walsh wrote:

> On Sat, 2003-02-22 at 17:18, Martin Pycko wrote:
> > Actually now you can use SIP_CODEC variable
> >
> > eg:
> >
> > [sip-context]
> > exten => 8500,1,SetVar,SIP_CODEC=alaw
> > exten => 8500,2,VoiceMailMain
> > ....
> >
> > now when you normally have
> > dissallow=all
> > allow=g729
> > in sip.conf configuration file ... then when you place
> > a call with your SIP phone to 8500 asterisk will
> > force your phone to talk with alaw codec.
> >
> > regards
> > Martin
>
> Does this also control the codec asterisk is using to talk to the remote
> device?
>
> I believe the problem with calling FWD callers outbound from an asterisk
> server is related to that, because I've eliminated everything else I can
> think of.
>
> Using the above line, it is working at forcing my sjphone to use alaw,
> or ulaw as I configure.
>
> I noticed when using SJPhone to register directly to FWD, and I call
> another FWD caller is also uses one or the other.
>
> So I'm wonder if it is possible that asterisk is using another codec
> when trying to talk to the remote device.
>
> When I use estera softphone with asterisk, and receive a call via fwd, I
> get an error "the media negotiation failed" which seems to support my
> theory.
>
> --
> William Walsh <william at wxw.org>
> Jabber: william at wxw.biz
>
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