An apparatus for inclusion in a mobile device , the apparatus comprising: a processing element, wherein the processing element is configured to: establish Wi-Fi communication with a cellular carrier over a Wi-Fi network ; register, with an IMS server, first destination information associated with the Wi-Fi communication ; register, with the IMS server, second destination information associated with the cellular communication ; wherein the first destination information is a first IP address and the second destination information is a second IP address, or the first destination information is a first port number and a first IP address and the second destination information is a second port number and the first IP address; wherein upon occurrence of a mobile terminating call from the cellular carrier, an incoming call notification on the Wi-Fi network is transmitted to the apparatus using the first destination information, or an incoming call notification on the cellular network is transmitted to the apparatus using the second destination information; and wherein the apparatus is further configured to receive and respond to the incoming call notification on the cellular network by answering the call using the Wi-Fi network based at least in part on a policy type indicating a preference for Wi-Fi communication; and wherein the apparatus is further configured to receive and respond to the incoming call notification on the Wi-Fi network by answering the call using the cellular network based at least in part on a policy type indicating a preference for cellular communication. a processing element, wherein the processing element is configured to: establish Wi-Fi communication with a cellular carrier over a Wi-Fi network ; register, with an IMS server, first destination information associated with the Wi-Fi communication ; register, with the IMS server, second destination information associated with the cellular communication ; establish Wi-Fi communication with a cellular carrier over a Wi-Fi network ; register, with an IMS server, first destination information associated with the Wi-Fi communication ; register, with the IMS server, second destination information associated with the cellular communication ; wherein the first destination information is a first IP address and the second destination information is a second IP address, or the first destination information is a first port number and a first IP address and the second destination information is a second port number and the first IP address; wherein upon occurrence of a mobile terminating call from the cellular carrier, an incoming call notification on the Wi-Fi network is transmitted to the apparatus using the first destination information, or an incoming call notification on the cellular network is transmitted to the apparatus using the second destination information; and wherein the apparatus is further configured to receive and respond to the incoming call notification on the cellular network by answering the call using the Wi-Fi network based at least in part on a policy type indicating a preference for Wi-Fi communication; and wherein the apparatus is further configured to receive and respond to the incoming call notification on the Wi-Fi network by answering the call using the cellular network based at least in part on a policy type indicating a preference for cellular communication. <EOS>