SIP MESSAGE PROCESSING

A method of processing Session Initiation Protocol (SIP) signalling messages in a telecommunications network is provided. The method includes, at a SIP routing element, maintaining a routing database containing routing data for routing SIP signalling messages between SIP network elements, maintaining a group of simultaneously active modes including at least a SIP proxy server stateless mode and a SIP proxy server stateful mode, receiving a plurality of SIP signalling messages from SIP network elements, routing at least some of the received SIP signalling messages with reference to the routing database according to a SIP proxy server stateless mode, and routing at least some of the received messages with reference to the routing database according to a SIP proxy server stateful mode.