Voice/SIP Query - G726r32 Payload Type

Hi Group,

Can anyone please help me out with this issue as I couldn't find a proper
solution or documentation anywhere on the internet.

In a Cisco TDM/SIP gateway or any voice gateway for that matter, is there a
way of changing the payload type mapping for the G726r32 codec.?
I know this RFC 1890 thing, suggesting the initial use of PT 2 for g726r32
and then it being deprecated in RFC 3551 . As I understand, G726r32 should
now be dynamically assigned a PT, but Cisco IOS {12.4(25)b and even 15.0M }
does not seem to do that. The problem I am running into is, the GW receives
an INVITE from a Non-Cisco SIP GW, with G726r32 PT=96 . The Cisco GW,
however, rejects this with a 488 Not acceptable, because it maps PT 2 (and
not 96) to g726r32 .
An outbound call from the Cisco GW goes as PT 2 and is accepted by the far
end , getting negotiated at the same value = 2. I have tried freeing up the
PT 96, which is by default assigned to FAX, by changing the FAX one to
something else. I can't change the PSTN GW parameters due to administrative
and other reasons.
Has anyone else faced such an issue before ?

Any pointers are greatly appreciated.

Thanks,
Ravi

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Received on Sun Sep 19 2010 - 05:26:29 ART