Patent ID: 8625433

Claim:
A method of enabling redundancy for a Home Subscriber Server (HSS) of an Internet Protocol (IP) Multimedia Subsystem (IMS) with redundancy being provided by a plurality of HSS instances, where the data for each of a plurality of users is stored by more than one of the HSS instances, the method comprising: arranging for a client node of the IMS to be provided with details of a proxy HSS representing the HSS instances in response to an inquiry from the client node, the details including a destination host Attribute Value Pair of the proxy HSS; and the proxy HSS: selecting an appropriate one of the HSS instances to handle a request received at the proxy HSS from the client node to obtain a selected HSS instance, the request including the destination host Attribute Value Pair of the proxy HSS provided to the client node; changing the destination host Attribute Value Pair received in the request based on the selected HSS instance; and forwarding the request to the selected HSS instance for handling.