Asterisk 1.4.6 interoperability problem with BTS 10200


We have cisco BTS (Border Telephony Switch) softswitch and asterisk (1.4.6 version),

The issue is for the following scenario, asterisk does not undestand 200OK message coming from CiscoBTS10200.

The call is originated by PAP2 and terminated by Remote gateway over asterisk and BTS.


The problem seems asterisk not able to undestand media attribute in SDP message whenever it contains following format:


If 200 OK message contains a=rtpmap:0 PCMU/8000 (the absence of /1), then call establishes successfully.

The BTS sends back the 200 OK with SDP message containing a=rtpmap:0 PCMU/8000/1, while the Tribox sends the original INVITE with a=rtpmap:0 PCMU/8000.

While both are semantically equivalent (the absence of the /1 indicates that there is a single audio channel),

I suspect there is a direct string match in the SDP handling code in the asterisk that does not take this into consideration.

Has any one experienced such a problem? Is there a way to force asterisk to understand SDP that contains attributes with a=rtpmap:0 PCMU/8000/1 format?

Waiting for your reply,

Best Regards