You are being offered two media streams. You may accept both, accept
audio and reject image, accept image and reject audio, or even answer
the call while rejecting both streams. (The latter is not common and
probably not very friendly - better to reject with 488 in that case.)
If you are capable of both audio and image, you should probably accept
both. Then you can wait to see what arrives. If you are sending, send
whichever you have to send, or even both.
Paul
SungWoo Lee wrote:
> Dear all,
>
> I have a question regarding receiving INVITE which has both audio and image
> mediadescriptor in its SDP. In this case, I don't know which mediadescriptor
> I should take, and I am not even sure whether this is legal format or not.
> Following is the sample incoming INVITE message that I received. If this is
> the initial INVITE, am I supposed to ignore FAX thing and take audio only?
> What if I receive this when I am trying to send FAX and the receiver side
> sends this re-INVITE to switch over to T.38 mode? Is there any RFCs regarding
> this issue? Looking forward to your answers.
>
> INVITE sip:[EMAIL PROTECTED]:5060 SIP/2.0
> FROM: <sip:[EMAIL
> PROTECTED]:5060;transport=tcp>;epid=765FF3B2D3;tag=9e148ff751
> TO: <sip:[EMAIL
> PROTECTED]:5060;transport=tcp>;tag=5614b60-afea878-13c4-50022-d4-47032be0-d4
> CSEQ: 1 INVITE
> CALL-ID: 55fde78-afea878-13c4-50022-d4-35449e22-d4
> MAX-FORWARDS: 70
> VIA: SIP/2.0/TCP 10.254.168.129:1593;branch=z9hG4bKfc5951b3
> CONTACT:
> <sip:exum.xxx.local:5065;transport=Tcp;maddr=10.254.168.129;ms-opaque=15a74095d736a37f>
> CONTENT-LENGTH: 282
> USER-AGENT: XXXX
> CONTENT-TYPE: application/sdp
>
> v=0
> o=- 0 1 IN IP4 10.254.168.129
> s=session
> c=IN IP4 10.254.168.129
> t=0 0
> m=audio 6353 RTP/AVP 0 8 101 13
> a=rtpmap:0 PCMU/8000/1
> a=rtpmap:8 PCMA/8000/1
> a=rtpmap:101 telephone-event/8000
> m=image 1592 udptl t38
> a=T38FaxRateManagement:transferredTCF
> a=T38FaxUdpEC:t38UDPFEC
>
>
> Sungwoo
>
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