Well, CANCEL is used to cancel any pending transaction. Since MG initiated the transaction, only it can CANCEL it. UAS can respond with some error message etc (if any) and on this response MG can should send ACK immediately which means end of transaction. MG can send CANCEL anytime after sending INVITE & before final response (error or no error). I hope this helps you.
Vipul Rastogi Engineer, Business Management Team Telecommunication Network Business Samsung Electronics CO, LTD Suwon P.O.BOX 105, 416 Korea 442-600 MO 010-9530-0354 ----- Original Message ----- From: "Jagan Mohan" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Wednesday, November 14, 2007 9:04 PM Subject: [Sip-implementors] UAS sending a CANCEL > Hi All, > > I have the following call flow: > > PSTN===Media Gateway-----UAS > > Call flow is made from PSTN phone to UAS. > > Media --------------UAS > Gateway > > INVITE--------> > <--------100 Trying > <--------180 Ringing > > At this point, can UAS send a CANCEL to the media gateway? > > From the discussion in various mailing lists, I understand that UAS can > not send a CANCEL request in this scenario. It can send a 4xx/6xx > > But, I could not find any RFC which talks about this. Could any one > please provide info. on the RFC which talks about the above scenario? > > TIA, > Jagan > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > > _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
