Handle SIP CANCEL messages properly to prevent spurious missed calls
When using single number reach and an incoming call is picked up on a desk phone, the mobile client shows a missed call. The call manager is correctly sending a SIP CANCEL with cause=200 (call completed elsewhere) but Skype for Business ignores this. Please correctly interpret these SIP messages and avoid generating spurious missed calls on the client.
Matthias Uschok commented
It seems like Skype is parsing the reason string and expects it to contain something like
and flatout rejects the CANCEL with cause 200, thereby assuming a missed call. Accepting RFC-compliant CANCEL requests would make the lives of admins a lot easier, since most PBX won't add the extended 'ms-acceptedby'-header. Asterisk certainly doesn't.
Thanks in advance!