Patent ID: 8218462

Claim:
An apparatus, comprising: a network infrastructure device that comprises a service control point component, an application server component, a first external interface, and a second external interface; wherein the service control point component emulates a service control point through the first external interface to communicates with a first telecommunication network through the first external interface, wherein the first telecommunication network comprises a legacy cellular telecommunication network with a home location register; wherein the application server component emulates an application server to communicates with a second telecommunication network through the second external interface, wherein the second telecommunication network comprises an IP multimedia subsystem (IMS) telecommunication network with a home subscriber server; wherein the service control point component communicates with the application server component through an internal interface; wherein the network infrastructure device, the home subscriber server, and the home location register are distinct from each other; wherein the network infrastructure device allows a mobile communication device that has a first registration in the first telecommunication network and a second registration in the second telecommunication network to receive, through the second telecommunication network, a call directed to the first registration; wherein the home location register of the first telecommunication network maintains the first registration and the home subscriber server of the second telecommunication network maintains the second registration; wherein the first telecommunication network is unable to directly query the second telecommunication network for a status of the second registration; wherein the service control point component receives a query message from the first telecommunication network through the first external interface and communicates the query message to the application server component through the internal interface; wherein the application server component checks for a recent failure flag upon receipt of the query message and sends a continuation message to the first telecommunication network if the recent failure flag exists, wherein the recent failure flag is associated with the call to indicate the failed delivery of the call through the second telecommunication network; wherein the application server component obtains the status of the second registration through the second external interface if the recent failure flag does not exist; wherein the network infrastructure device employs the status of the second registration to allow the mobile communication device to receive the call directed to the first registration through the second telecommunication network.