The present invention enables a home network operator to control roaming
of its subscribers. A mobile initiates a location update procedure by
sending a "Location Updating" message containing an IMSI and a LAI to a
MSC/VLR in a visited network. The MSC/VLR in turn sends an
"UpdateLocation" message including the LAI, the IMSI, and a VLR address
to a HLR in a home network. A Roaming Enhancement Node (REN) in the home
network intercepts the "UpdateLocation" message and determines whether to
continue registration based on the LAI in the message. If the mobile is
roaming in a location area that is restricted, the REN sends a rejection
response with a rejection cause to the MSC/VLR. The MSC/VLR in turn sends
another rejection response with the same rejection cause to the mobile.
If the mobile is roaming in a location area that is not restricted, the
"UpdateLocation" message is forwarded to the HLR.