摘要:
A method and system for setting up and maintaining an IMS session. The method comprising transmitting an invite message from a registered user equipment, forwarding the invite message to a selected SIP proxy (P-CSCF), forwarding the invite message to a specified SIP server (S-CSCF) and relaying said invite message to a destination. The invite message contains a header and a payload. The header includes an identifier for the load balancing node. The load balancing node is assigned to the user equipment. There are at least two load balancing node, a primary and a secondary load balancing node. The identifier for the load balancing node does not change even if there is a failure of one of a primary load balancing node, the P-CSCFs or S-CSCFs. During registration, the routing information for the load balancing node is added into both via and record-route headers in a SIP registration request.