Patent ID: 9544178
Date: 2017-01-10
CPC Classifications: H04L

Claim:
1. A method of handling a Session Initiation Protocol message in a communications network to enable a remote node in the communications network to be able to determine a current target of the Session Initiation Protocol message, the method comprising: at a node in the network, receiving a Session Initiation Protocol message, the Session Initiation Protocol message comprising a Request-URI header; rewriting the Request-URI header in the Session Initiation Protocol message; checking whether the rewriting was caused by: processing a target header associated with the Session Initiation Protocol message in dependence on which type of operation caused the rewriting; and sending the Session Initiation Protocol message to a further node; wherein when the rewriting is caused by the first type of operation and a current target address is not already present in the target header of the Session Initiation Protocol message the processing includes writing information identifying the current target to said target header of the Session Initiation Protocol message to enable the remote node to determine the current target; wherein when the rewriting is caused by the second type of operation and the target header is not present in the Session Initiation Protocol message, the processing further includes inserting said target header in the Session Initiation Protocol message and including in said inserted target header information identifying the current target to enable the remote node to determine the current target; wherein when the rewriting was caused by the second type of operation and the target header is already present in the Session Initiation Protocol message, the processing further includes leaving the target header unchanged to enable the remote node to determine the current target; and wherein the target header is a separate information element from the Request-URI.