asterisk users - May 2008 - IAX IP Trunk + GSM Codec and Noise in the Polycom IP Phone 320

Hi All;

I have an IP Trunk between two asterisk box (A and B),
when side A originate calls via the digium card from
the fxo port, and need to talk with side B at Polycom
320, then there is a disturbance will be heared on
Polcyom 320.

Note that used codec for the trunk between the side A
and B is GSM, while Polcyom is using alaw codec.

This problem happens only when originator is coming
via the PSTN in side A and calling Polycom at side B,
but if FXS port in side A is calling Polycom at side B
then no disturbance.

In other words, the problem happens only when someone
call from landline or mobile line to Asterisk in side
A, and then dial the extension of Polycom connected to
Asterisk in side B.

To what could be the problem?
Regards
Bilal


     
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