If you’ve been interested in making Mac Messenger 7 work with H.263 devices, unfortunately the outlook is not good. It appears that even though Mac Messenger 7 adds H.263 as a candidate in its SDP, it doesn’t actually support the H.263 codec. Tom Laciano and I worked on this and unfortunately there’s a bug in Mac Messenger 7 that causes it to add H.263 as a codec event though it doesn’t actually support it. More detail that I provided to Tom is in his blog:
I’ll repost the SDP info here. In my case I was calling from Mac Messenger to a Polycom HDX.
User-Agent: UCCP/2.0.6362.0 MM/7.0.4663.2 (Mac Messenger 7.0.2)
...
a=rtpmap:121 x-rtvc1/90000
a=rtpmap:34 H263/90000
Calling from Mac Messenger to an HDX, the Mac just sends a BYE message with no error code anywhere in the SIP trace.
Calling from the HDX to Mac Messenger you see the same codec in the invite:
a=rtpmap:34 H263/90000
But Mac Messenger rejects it with a 488.
Start-Line: SIP/2.0 488 Not Acceptable Here
...
User-Agent: UCCP/2.0.6362.0 MM/7.0.4663.2 (Mac Messenger 7.0.2)
Steve Lessard did the original investigation on this and has posted some info on his blog as well. Hopefully this gets corrected in future updates of Mac Messenger to get the product on par with Office Communicator.
