An IMS network is an architectural framework for delivering Internet Protocol (IP) multimedia services. Session Initiation Protocol (SIP) is used for signalling within the IMS network; i.e. for routing request messages and response messages within the network. While designing, maintaining and/or servicing IMS networks, it may be necessary to analyse SIP requests and responses in the IMS network, traversing nodes or proxies such as a “Proxy Call Session Control Function” (P-CSCF), a “Serving Call Session Control Function” (S-CSCF), an “Interrogating Call Session Control Function” (I-CSCF), an “Interconnect Border Control Function” (IBCF), and other nodes.
It is known that when SIP signalling messages traverse an IMS network via the abovementioned nodes, signalling information may be generated by the abovementioned nodes, on entry of the SIP signalling messages in the respective node and on departure of the SIP signalling messages from the respective node. Such information may be in the form of trace records generated by the nodes, which may be sent by the nodes to a server arranged for collecting such trace records and assembling these records into a single trace pertaining to a single session establishment that took place within the IMS network.
With the advent of “IMS roaming” and “IMS interconnect”, whereby SIP sessions may span two or more IMS networks, the number of SIP proxies that SIP sessions will traverse increases. As a consequence, the collecting trace information server, e.g. debug server, needs to perform extensive post-processing on collected trace records to retrieve the desired information belonging to the session to be analysed. Elaborate book keeping and a dedicated server is required to assemble the information for analysing a particular session.