[SIPForum-discussion] Need Help in SIPP for flow of RTP

Halit Sakca sakcahalit at hotmail.com
Mon Dec 31 12:15:30 UTC 2007

Hey Jeff,
Regarding your question I checked the RFCs and found out that;
SIP is a transactional protocol: interactions between components take place in a series of independentmessage exchanges. Specifically, a SIP transaction consists of a single request and any responses to thatrequest, which include zero or more provisional responses and one or more final responses. In the caseof a transaction where the request was an INVITE (known as an INVITE transaction), the transaction alsoincludes the ACK only if the final response was not a 2xx response. If the response was a 2xx, the ACK isnot considered part of the transaction.The reason for this separation is rooted in the importance of delivering all 200 (OK) responses to an INVITE to theUAC. To deliver them all to the UAC, the UAS alone takes responsibility for retransmitting them (see Section 13.3.1),and the UAC alone takes responsibility for acknowledging them with ACK (see Section 13.2.2). Since this ACK isretransmitted only by the UAC, it is effectively considered its own transaction.
hopefully helpful for you ;)
Happy new year!
Selamlar,Halit Sakca

> Date: Thu, 27 Dec 2007 05:59:39 +0300> From: effery97 at gmail.com> To: discussion at sipforum.org> Subject: Re: [SIPForum-discussion] Need Help in SIPP for flow of RTP> > Why ACK have different trasaction ID then INVITE?
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