[ Line 1  ] SIP/2.0 200 OK

[ Line 2  ] Via: SIP/2.0/UDP 192.168.1.15:5060;branch=z9hG4bK3933794001smg;transport=UDP

[ Line 3  ] From: <sip:+11234567890@ims.sharetechnote.com>;tag=2504745718

[ Line 4  ] To: <sip:+11234567890@ims.sharetechnote.com>;tag=987654321

[ Line 5  ] Call-ID: 500949143@192.168.1.15

[ Line 6  ] CSeq: 1 REGISTER

[ Line 7  ] Allow: INVITE, ACK, CANCEL, BYE, PRACK, MESSAGE

[ Line 8  ] Supported: 100rel, timer

This SIP message clip highlights the following parameters: Via, CSeq, Call-ID, From, To, Supported, Allow. Use these fields to correlate routing, dialog identity, transaction sequencing, registration/session state, security context, and media negotiation for this part of the procedure.

[ Line 9  ] Date: Tue, 27 Mar 2012 19:49:16 GMT

[ Line 10 ] Contact: <sip:+11234567890@192.168.1.15:5060>;expires=3600

[ Line 11 ] Content-Length: 0

[ Line 7  ] Allow:

This SIP message clip highlights the following parameters: Contact, Expires, Content-Length, Allow. Use these fields to correlate routing, dialog identity, transaction sequencing, registration/session state, security context, and media negotiation for this part of the procedure.

This Field lists the set of methods supported by the UA which generate the message. (See "20.5 Allow" of  RFC 3261).

[ Line 8  ] Supported:

This SIP message clip highlights the following parameters: Supported. Use these fields to correlate routing, dialog identity, transaction sequencing, registration/session state, security context, and media negotiation for this part of the procedure.

This field enumerates all the extensions supported by the UAC(User Agent Client) or UAS(User Agent Server). (See "20.37 Supported" of  RFC 3261).