[SIPForum-discussion] Video Phones not acknowledging SIP 200 OK Messages

Franz Edler franz.edler at technikum-wien.at
Sun Jul 24 18:51:32 UTC 2011

Hi Segun,
> Find attached the logfile from the IP-PBX and also debug files and logs
> the Video phone (Helios IP Door Station from 2N)

Based on the tracefile (pcap file) the situation is clear:
The client includes in INVITE media lines for audio and video (packet 183)
in its SDP offer but the server only includes audio in its SDP answer in 200
OK (packet 191).
This is a violation of RFC 3264 §6
	For each "m=" line in the offer, there MUST be a corresponding "m="
line in the answer. The answer MUST contain exactly the same number of "m="
lines as the offer.

The server (splicecom SIP) does not conform to RFC 3264.


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