RE: [Sip-implementors] Definition of Call-ID

[Chris Boulton]

<<< See comments >>>>   -----Original Message----- From: Hemant Pandey [mailto:[EMAIL PROTECTED] Sent: 28 February 2003 03:31 To: [EMAIL PROTECTED] Subject: [Sip-implementors] Definition of Call-ID   Dear All,        To implement multimedia services in 3G network, I recently started studying RFC3261 for SIP protocol. Since i am new to SIP protocol, i have confusion about few terms used in RFC3261. 1. Call-ID   What exactly this Call-ID identifies?   <<<< The Call-ID is seen as a unique identifier for a particular call.  It is then used by the originating client to match responses appropriately.      In its definition in RFC3261, Call-ID acts as a unique identifier to group together a series of messages. So what does this group means?   <<<<A Sip call consists of a series of requests/responses.  Clients (both client and server) need a mechanism to associate(group) such requests/responses.>>>>   2. What is target refresh requests? How these requests could be differentiated with other requests?               <<<< It is a ‘keep alive’ mechanism for sip.  They are differentiated by incrementing the sequence number of the new request (CSEQ).   3. which RFC should be referred for latest SIP call flows examples?               <<<< See draft-ietf-sipping-basic-call-flows-01.txt from the ietf sipping group. >>>>   i will be obliged if any one help to clear these points.   Regards   Hemant Pandey