Call routing for IP multimedia subsystem users

A method of routing an IP Multimedia Subsystem, IMS, connection request sent by a user of a third party service, User A, towards a peer third party service user, User B, where the originating identity and target identity fields contain respectively external third party identities of User A and User B. The method comprises receiving said request at an IMS Access Gateway to an IMS network, and extracting said external identities and determining whether the extracted external identities are registered in respect of a wildcarded IMPU or wildcarded IMPUs that in turn is or are registered in the IMS network. In the event that these are registered, it is determined whether or not service logic is to be executed in the IMS network for both User A and User B and, if not, an IMS Edge Node routable identity associated with User B is determined. The IMS Edge Node routable identity is used to forward the IMS connection request to a terminating side IMS Edge Node.