Hi Benny and all, I'm trying to implement a simple UAS to handle incoming INVITE requests. I first create the uas dialog, the sdp session and the invite uas session. At this point, I've obtained these logs: 16:52:12.651 sip_endpoint.c Processing incoming message: Request msg INVITE/cseq=101 (rdata0x9a86694) 16:52:12.651 tsx0x9a94bdc Transaction created for Request msg INVITE/cseq=101 (rdata0x9a86694) 16:52:12.651 tsx0x9a94bdc Incoming Request msg INVITE/cseq=101 (rdata0x9a86694) in state Null 16:52:12.651 tsx0x9a94bdc State changed from Null to Trying, event=RX_MSG 16:52:12.651 dlg0x9a943d4 Transaction tsx0x9a94bdc state changed to Trying 16:52:12.651 dlg0x9a943d4 UAS dialog created 16:52:12.651 dlg0x9a943d4 Module mod-invite added as dialog usage, data=0x9a956a0 16:52:12.651 dlg0x9a943d4 Session count inc to 2 by mod-invite 16:52:12.651 inv0x9a943d4 UAS invite session created for dialog dlg0x9a943d4 Now, if I want to send a 100 Trying provisonal response, I have to call the "pjsip_inv_initial_answer" function (or something like that). But, from RFC3261 - section 17.2.1: " When a server transaction is constructed for a request, it enters in the "Proceeding" state. The server transaction MUST generate a 100 (Trying) response unless it knows that the TU will generate a provisonal or a final response within 200ms [...] This provisonal response is needed to quench retransmission rapidily in order to avoid network congestion". Despite that, I've noticed that the transaction we create is not in the Proceeding state (it enters only after the pjsip_inv_initial_answer call): 17:01:53.384 endpoint Response msg 100/INVITE/cseq=101 (tdta0x8d0afc8) created 17:01:53.384 dlg0x8d083d4 Initial answer Response msg 100/INVITE/cseq=101 (tdta0x8d0afc8) 17:01:53.384 inv0x8d083d4 Sending Response msg 100/INVITE/cseq=101 (tdta0x8d0afc8) 17:01:53.384 dlg0x8d083d4 Sending Response msg 100/INVITE/cseq=101 (tdta0x8d0afc8) 17:01:53.384 tsx0x8d08bdc Sending Response msg 100/INVITE/cseq=101 (tdta0x8d0afc8) in state Trying 17:01:53.384 sip_resolve.c Target '10.13.0.104:5060' type=UDP resolved to '10.13.0.104:5060' type=UDP (UDP transport) 17:01:53.384 tsx0x8d08bdc State changed from Trying to Proceeding, event=TX_MSG 17:01:53.384 dlg0x8d083d4 Transaction tsx0x8d08bdc state changed to Proceeding 17:01:53.384 myapp.c Call state changed to INCOMING I think this might be wrong. What happens if I wait before creating the provisonal response? Don't you think it would be better to automatically generate the 100 Trying response as soon as possible (e.g. inside the pjsip_inv_create_uas) and then give the control back to the user? Thanks, Giorgio
