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Unformatted text preview: session, RTP packets are distinguished from RTCP packets by using distinct port numbers R12. Every SIP user has an associated registrar. SIP registrar keeps track of users current IP address. When a user switches to new SIP device, the new device sends a new registrar message, indicating the new IP address. If the user remains at the same device for a extended period of time, the device will send refresh registrar messages indicating the most recently sent IP address is still valid. The SIP registrar translates fixed human identifiers like email@example.com to dynamic IP addresses. In SIP, the registrar provides remote systems with the new IP address so that they can connect to the mobile machine directly. Home Agents in Mobile IP provide a tunneling service between the home IP address and the mobile address. Thus, all connections going to the home address are transparently forwarded to the mobile address...
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- Spring '08