Patent ID: 8542670

Claim:
A method for routing a call for a user element having a directory number from a first domain into a second domain, wherein the user element is homed in the first domain and roaming in the second domain, comprising: receiving a first message identifying the user element and indicating that an incoming call intended for the user element has been routed to a first gateway node for the first domain; temporarily assigning a temporary inter-domain routing number for the incoming call intended for the user element; and providing the temporary inter-domain routing number for the first gateway node to use to route the incoming call into the second domain, wherein one of the first and second domains is a circuit-switched subsystem and another of the first and second domains is a multimedia subsystem, wherein the temporary inter-domain routing number identifies a second gateway node for the second domain, such that the incoming call is routed from the first gateway node of the first domain to the second gateway node of the second domain using the temporary inter-domain routing number and the temporary inter-domain routing number is released after routing the incoming call.