com;branch=z9hG4bKnashds7 To: k<sip:notify@handbook.com> From: ip:subscribe@handbook.com>;tag=12341234 Call-ID: 10275342@handbook.com CSeq: 1 SUBSCRIBE Max-Forwards: 70 Expires: 3600 Event: presence Accept: application/pidf+xml Contact: sip:user@handbook.com Content-Length: 0 M2: The presence server for notify@handbook.com processes the subscrip- tion request and creates a new subscription. A 200 (OK) response is sent to confirm the subscription. SIP/2.0 200 OK Via: SIP/2.0/UDP xample.com;branch=z9hG4bKnashds7 received=168.0.2.5 To: sip:notify@handbook.com>;tag=abcd1234 From: sip:subscribe@handbook.com>;tag=12341234 Call-ID: 0275342@handbook.com CSeq: 1 SUBSCRIBE Contact: sip:server.handbook.com Expires: 3600 Content-Length: 0 M3: In order to complete the process, the presence server sends the sub- scriber a NOTIFY with the current presence information of the presentity. NOTIFY sip: :user@handbook.com SIP/2.0 Via: SIP/2.0/UDPserver.handbook.com;branch=z9hG4bk8sdf2 To: <sip:subscribe@handbook.com>;tag=12341234 From: <sip:notify@handbook.com>;tag=abcd1234 Call-ID: 10275342@handbook.com Event: presence CSeq: 1 NOTIFY Max-Forwards: : 70 Subscription-State: active; expires=3599 Contact: sip:server.handbook.co Content-Type: application/pidf+xml Content-Length: [PIDF Document] © 2009 by Taylor & Francis Group, LLC SIP Event Notification and Presence Information M4: The watcher confirms receipt of the NOTIFY request. SIP/2.0 200 OK Via: SIP/2.0/UDP server.handbook.com;branch=z9hG4bk8sdf2; received: 168.0.2.6 To: ksip:subscribe@handbook.com>;tag=12341234 From: <sip:notify@handbook.com>;tag=abcd1234 Call-ID: 10275342@handbook.com CSeq: 1 NOTIFY Content-Length: 0 M5: The presence server detects that a reportable change has been made to the presentity's presence information and sends a new notification to the watcher. NOTIFY sip:user@handbook.com SIP/2.0 Via: SIP/2.0/UDP server.handbook.com:branch=z9hG4bk4cd42a To: sip:subscribe@handbook.com>;tag=12341234 From: <sip:notify@handbook.com>;tag=abcd1234 Call-ID: 10275342@handboo