[asterisk-users] G.722: ast_channel_make_compatible failure

[Kevin P. Fleming]

Ondrej Valousek wrote:

> My problem is, that the phone offering g722 could do alaw as well.
> I expected asterisk should just chose alaw for the communication - no
> transcoding is necessary then...

That is not how Asterisk works, and is well known in the community as
something that users would like to see changed, but has not yet been
done. Asterisk negotiates the codecs (formats) for each call leg pretty
much independently of the others, so if a G.722 endpoint initiates the
first call leg, and the destination call leg cannot accept G.722, and
there is no transcoder available, then the call will fail. If the
non-G.722 endpoint initiates the first call leg then the call will
likely go through, which is somewhat unfortunate :-)

-- 
Kevin P. Fleming
Director of Software Technologies
Digium, Inc. - "The Genuine Asterisk Experience" (TM)