[asterisk-users] problem with T.38 media headers

[Alex Balashov]

This is not a problem.  Asterisk is under no obligation to offer an 
audio codec in return.

mario staphorst wrote:

> Hi Guys,
> 
> Something I have noticed while dealing with T.38 and re-invites in 
> Asterisk 1.4.22.
> 
> I have a provider who re-invites with the following sdp (message flow
> PROVIDER_EQPMT -> ASTERISK):
> 
> """
> .
> v=0.
> o=SIP_5F9 123456 654322 IN IP4 CONN_IP_PROVIDER.
> s=-.
> c=IN IP4 CONN_IP_PROVIDER.
> t=0 0.
> m=audio 0 RTP/AVP 0.
> m=image 26858 udptl t38.
> a=T38FaxMaxBuffer:288.
> a=T38FaxRateManagement:transferredTCF.
> a=T38FaxUdpEC:t38UDPRedundancy.
> """
> 
> The answer coming from asterisk in this case is:
> 
> """
> .
> v=0.
> o=root 3484 3485 IN IP4 CONN_IP_ASTERISK.
> s=session.
> c=IN IP4 CONN_IP_ASTERISK.
> t=0 0.
> m=image 4653 udptl t38.
> a=T38FaxVersion:0.
> a=T38MaxBitRate:9600.
> a=T38FaxRateManagement:transferredTCF.
> a=T38FaxMaxBuffer:200.
> a=T38FaxMaxDatagram:200.
> a=T38FaxUdpEC:t38UDPRedundancy.
> """
> 
> I see a problem here since the number of matched media streams from the
> offer does not match with the number of matched media streams in reply
> from asterisk (notice the m=audio 0 RTP/AVP 0 not present in the reply).
> 
> Please let me know if there are workarounds on this issue, or if this
> could be a bug on asterisk side.
> 
> Best regards,
> 
> Mario Staphorst
> 
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-- 
Alex Balashov
Evariste Systems
Web    : http://www.evaristesys.com/
Tel    : (+1) (678) 954-0670
Direct : (+1) (678) 954-0671
Mobile : (+1) (678) 237-1775