21 Mar
2009
21 Mar
'09
2:46 a.m.
Gabriel Kuri wrote:
once the FAX tone is detected on the PSTN side, FS receives a T.38 re-INVITE from the provider and FS sends back a 488/Not Acceptable (proxy_media=false). at that point the provider than attempts fallback to PCMU with another reINVITE ...
This part is interesting, and the subject of a discussion we had recently. A number of systems try that second re-invite after a 488, but the SIP specs say the call is pretty much dead after the 488 message is exchanged. Are they just hoping that maybe the other end will be non-compliant enough to keep the call alive, and recover its media mode, or haven't they read the specs? Steve