Internet Communications Using SIP : Delivering VoIP and Multimedia Services With Session Initiation Protocol {2Nd Ed.}

Figure 19.4 Call flow for voicemail

1 HTTP GET

WEB CALLER CONTROLLER VOICEMAIL SERVER

3 200 OK

9 200 OK

5 INVITE

1 - Caller selects

voicemail URI on web

server. Web server

informs controller.

2 - Call setup from

controller to caller

with call on hold

4 - Controller reinvites

caller with SDP

pointing to voicemail

3 - Call setup to

voicemail

7 ACK

MEDIA

2 INVITE

4 ACK

10 ACK

11 HTTP 200 OK

8 re-INVITE

6 200 OK

SIP Component Services 329