Patent ID: 7555555
Filing Date: 2009-06-30
Classification: H04L

Abstract:
1. An SIP (Session Initiation Protocol)-based multimedia communication system, comprising SIP network service domains that provide mobility based on a logical SIP identifier allocated to each of users, and a global domain that integratively manages the SIP network service domains and allocates a global SIP identifier that is a lifelong number to each user to provide user-centered mobility, wherein each of the SIP network service domain comprises: a user agent that transmits request/response messages between users to set up, correct, and cancel a call, and when contact information of the user agent is registered and registration of the contact information is cancelled, requests to be informed of a state change in registration information; and an SIP network server that carries out message routing between user agents and informs of the contact information of the user agents during message routing.