I'm curious if anyone might have some insight into whether or not T.38 compliant gateways should be able to handle the receipt of an initial SIP INVITE specifying T.38 in SDP ? I'm running into some gateway vendors that are claiming that the call must originate as a voice call and then switch to fax but cannot originate as a fax call. The specific scenario involves an application that only supports T.38 for fax that is trying to send faxes to the PSTN via a gateway.
Looking at the T.38 spec, section D.2.1.1 states: D.2.1.1 Call setup Call setup for Annex D/T.38 compliant implementations is based on SIP (Session Initiation Protocol) defined in RFC 2543. As in Annex B, implementations may operate in two distinct compatible environments: 1) A facsimile-only over IP environment - In this environment, no voice support is provided. The procedures and requirements of D.2.2.3 shall apply to implementations operating in this environment. 2) A facsimile and voice over IP environment - The procedures and requirements of this annex shall apply to implementations operating in this environment. One vendor is stating that an implementation that supports #2 does not need to support #1. In my mind, for these environments to be "compatible" a fax/voice environment (ex. gateway) would need to support receipt of calls from a fax-only environment (ex. T.38 application). Thoughts ? James _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
