Hi, First, you must always ACK the final response to the INVITE, no matter what it is, and no matter what other requests (ie a CANCEL to cancel the INVITE) you have sent. Second, currently it is allowed to send a BYE instead of a CANCEL. This has also recently been discussed on the SIP mailing list, so you may want to have a look in the archieves. So, I guess your flow would look something like this: UAC --INVITE----------> UAS UAC --BYE/CANCEL------> UAS UAC <--487(INVITE)----- UAS UAC <--200(BYE/CANCEL)- UAS UAC --ACK-------------> UAS There are also some special scenarios, ie when a 200(INVITE) from the UAS and a CANCEL from the UAC are sent at the same time. In this case, if the UAC sends a CANCEL, and still receive a 200 final response, the UAC shall ACK the final response and then send a BYE. If the final response is non-200 the UAC only needs to ACK the INVITE. Regards, Christer Holmberg Ericsson Finland Vijay Ramachandran Iyer wrote: > > Another question which I couldnt find an answer to in the spec. > Can a BYE be sent by a UAC immediately after an INVITE (without getting a > response to the INVITE?). Or is a BYE to be sent only after getting some > sort of reponse to the INVITE (thus enforcing the 3-phase-ness of > an invitation). > Also I think the 3-phase-ness of invitation is compromised when it > is said that a UAC on receiving a 200 OK to an INVITE may ACK or send a > BYE if it no longer wishes to talk to the UAS.. > Thus the above looks like: > > UAC --INVITE--> UAS > UAC <--200 OK-- UAS > UAC--BYE----> UAS (instead of an ACK) > UAC <--200OK(bye)-- UAS > (I am following RFC 2543) > > Thus now it become 4 phase!!! > > what is the current bis # ?? > > Vijay > > _______________________________________________ > Sip-implementors mailing list > [EMAIL PROTECTED] > http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
begin:vcard n:Holmberg;Christer tel;cell:+358-40-5604412 tel;work:+358-9-2992943 x-mozilla-html:FALSE org:Ericsson;IP Multimedia / Advanced Signalling Research Laboratory adr:;;;;;; version:2.1 email;internet:[EMAIL PROTECTED] title:System Designer fn:Christer Holmberg end:vcard
