A method of updating core domain information for use by a communication device (4) for routing a service for the communication device in a communication environment (2) including a core network (8) having a plurality of core domains (9, 11), and a plurality of radio access networks (6), each of the plurality of radio access networks being associated with at least one of the plurality of core domains, comprises generating (304) by the core network network information. The network information includes information identifying a preferred core domain for the communication device and a preferred radio access network and being based on network based parameters provided by the core network and connectivity information received from the communication device identifying the radio access networks of the plurality of radio access networks which are available to the communication device for communication. The method further comprises receiving (306) at the communication device from the core network the network information and updating (307) the core domain information in the communication device based on the network information. The updated core domain information is used by the communication device for routing a service.