Today's advanced communication devices are capable of seamlessly operating in a packet-switched IP network domain (using, for example, wireless LAN (WLAN) or Wi-MAX networks, etc.) as well as a circuit-switched cellular network domain. To facilitate such capability, current 3rd Generation Partnership Project (3GPP) standards specify a new, IP-based network architecture referred to as the IP multimedia subsystem (INS) which allows a communication device (referred to as user equipment or UE) to initiate calls to both IP-only subscribers and conventional circuit-switched telephony subscribers using either of the domains. There may arise a situation, however, where a wireless device, i.e., a UE device in 3GPP, is able to make a voice call to a called party using the circuit-switched network domain only because either no packet-switched network is available or the available networks in the packet-switched domain do not support the Voice-over-IP (VoIP) service. In such a situation, if the called party happens to be an IP-only subscriber and is identified with a Uniform Resource Indicator (URI), the originating UE may not be able to make the IP-based call since the UE device can effectuate only E.164 number-based calls while operating in the circuit-switched domain.
USPTO Backgrounds
USPTO Backgrounds