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

Figure 15.2 Terminal mobility: Precall scenario

Terminal mobility has to work also when the mobile host is moving between

networks during a SIP session. This is shown in Figure 15.3 when the mobile

user moves from Network 1 to Network 2.

Roaming

User

(Callee)

Corresponding

Host

(caller)

Home

Registrar

and Proxy

DHCP

Visited Network Internet Home Network

visited.org company.com

4 INVITE

1 INVITE

3 ACK

2 302 moved temporarily

5 200 OK

6 ACK

7 MEDIA

IP Address

258 Chapter 15