COMMUNICATION SYSTEM AND METHOD FOR USING SESSION INITIATION PROTOCOL IN A NETWORK ADDRESS TRANSLATION ENVIRONMENT

摘要

A communication system for using the session initiation protocol (SIP) in a network address translation (NAT) environment is provided, which includes a client, a relay server and a SIP server. The relay server is connected to the SIP server and connected to the client through a NAT server. The relay server is configured to establish connection with the client and register with the SIP server so as to allow direct communication between the client and the SIP server, thereby conducting authentication and management of the client and further solving the conventional problem of incompatibility between the SIP server and the client.