[Asterisk-Users] IAX2 codecs used asymmetric ?!!

[Branko Samardzic]

Hi,
I am trying to make following setup

PSTN --> Asterisk_1 ------- IAX2 stream over Internet -----> Asterisk_2 -->
PSTN
             ^
             |
          AGI control App

Basically this is calling card solution that accepts calls from PSTN of one
country
checks user credentials (PIN and access rights), collects destination number
and
establishes IAX2 connection with another Asterix server in different country
that
is used to terminate call on another PSTN.
So far I made everything working nice except one VERY important thing:

IAX2 stream over Internet is at least in one direction bearing 16 bit Signed
Linear PCM
data although I insisted on GSM codec. As link has limited bandwith (64kpbs)
it becomes
congested with single call.
My iax.conf files contain disallow=all and allow=gsm in general section on
both servers
but it is of no help.
Is there any chance to tweak IAX2 stream to be symetric (i.e. to bring GSM
encoded audio
in both directions) and how to achieve that.
Any help is appreciated.
Regards,
B.S.