An inter-working function selection system in a coupled data network is disclosed. The coupled data network includes a foreign network and a home network. The foreign network includes a foreign mobile switching center with a serving registration server. The home network includes a home mobile switching center with a home registration server and a plurality of unassigned home inter-working functions. A first end system is a subscriber to the home network and operates within the foreign network. The first end system includes an end registration agent to form a registration request, the end registration agent sending the registration request through the serving registration server to the home registration server, the home registration server including a module to select an active home inter-working function from the plurality of unassigned home inter-working functions based on the registration request.