Patent ID: 8102988

Claim:
In a third party tandem services network interconnecting a plurality of wireline and wireless carriers, a system for selectively directing a call originating from one of the plurality of carriers to a terminating switch presently serving a called subscriber unit of another of the plurality of carriers, said system comprising: a subscriber unit location register database maintained by at least one of the plurality of carriers connected to the third party tandem services network, the subscriber unit location register database containing information indicative of each subscriber unit's registration status and location for the at least one of the plurality of carriers; and a service control point (“SCP”) in communication with the subscriber unit location register database and including an SCP database of data indicative of an availability status of the called subscriber unit, wherein the subscriber unit location register database provides data representative of the registration status and location of the called subscriber unit, including one of either a routing destination number and an equivalent telephone number, to the SCP for updating of the SCP database; wherein the SCP is arranged to access the SCP database directly when a request for call-routing information is received from a third party tandem services network switch and to provide the call-routing information to the third party tandem services network switch; wherein if the SCP determines that the called subscriber unit is available, the SCP sends a third party tandem services network switch service switching point (“SSP”) the called subscriber unit's current service address to route the call to the terminating switch presently serving the called subscriber unit; and wherein if the SCP determines that the called subscriber unit is unavailable, the SCP sends a third party tandem services network switch service switching point (“SSP”) the information to route the call to a home switch of the another of the plurality of carriers for at least one of an location register database announcement, a voice mail, and another call treatment.