A system and method to assist in establishing a communication session to a mobile device having a registered IMS session in a visited network, or having both a registered IMS session and a circuit-switched session in a visited network. When a mobile device establishes an IMS session with an application service in a visited network, the address of the application service and the identity of the mobile device is transmitted to the Home Location Register (HLR) and/or Home Subscriber Server (HSS) associated with the mobile device. The HLR or HSS stores the address of the application service in conjunction with the identity of the mobile device. When requests to establish a communication session with the mobile device are made, the HLR or HSS provides the address of the application service that is associated with the mobile device in the visited network to allow a communication session to be established.