Patent ID: 8068480

Claim:
A first gateway connected to a PSTN, an IP network, and a mobile communications network including a base station configured to receive a communication source call from a mobile terminal in the mobile communications network, the first gateway comprising a control unit configured to perform handover through either the PSTN or the IP network, the first gateway being configured: d1) to receive from the base station a communication request relating to the communication source call and to determine whether the communication request is a handover call; and a) on determining, at d1, that the communication request is not a handover call, to perform a line exchange connection through the PSTN or a VoIP connection through the IP network depending upon the type of the communication source call; and d2) on determining, at d1, that the communication source call is a handover call, to determine whether the first gateway is managing the communication source call; and b) on determining, at d2, that the first gateway is managing the communication source call, to perform the handover through the PSTN or the IP network depending upon the type of the communication source call, the handover being performed by the first gateway; and d3) on determination, at d2, that the first gateway is not managing the communication source call, to interrogate a second gateway to determine whether the communication source call is being managed by the second gateway connected to the first gateway via the IP network; and c1) on determining, at d3, that the communication source call is not being managed by the second gateway, to perform the handover through the PSTN; and c2) on determining, at d3, that the second gateway is managing the communication source call, to perform the handover through the IP network by acquiring information relating to the source call from the second gateway, and taking over management of the communication source call from the second gateway.