Method and apparatus for call handover between different mobile radio networks

Claim 1

A method of inter-network call handover, for handing over a call from an initial communications network to a target communications network, comprising the steps of: establishing a call between a mobile subscriber unit and the initial communications network using a first identification number allocated to that unit in the initial network, identifying that a handover to the target network is desired providing the initial network with a second identification number allocated to the unit in the target network; initiating a call transfer request to establish a call to the unit in the target network using the second identification number and establishing a new link in the target network using the second identification number.

Claim 2

A method of inter-network call handover, for handing over a call from an initial communications network to a target communications network, comprising the steps of: establishing a call between a mobile subscriber unit and the initial communications network using a first identification number allocated to that unit in the initial network; pre-providing, to a predetermined node in the initial network, a second identification number allocated to the unit in the target network; identifying that a handover to the target network is desired; initiating a request to establish a call to the unit in the target network using the second identification number by providing a signal from the mobile subscriber unit to the predetermined node requesting a handover to the mobile subscriber unit identified by the second identification number; and establishing a new link in the target network using the second identification number.

Claim 4

A method according to either of claims 2 and 3, wherein the predetermined node is a cordless base station.

Claim 5

A method of inter-network call handover, for handing over a call between a mobile subscriber unit and a second party from an initial communications network to a target communications network, comprising the steps of: associating the mobile subscriber unit with a first identification number allocated to the mobile subscriber unit in the target network and with a predetermined node in the target network; establishing a call between the mobile subscriber unit and the initial communications network using a second identification number allocated to that unit in the initial network; establishing a communication path between the mobile subscriber unit and the predetermined node in the target network via the initial network; establishing a communication path between the predetermined node in the target network and the second party and linking, at the predetermined node, the two communication paths; identifying that a handover to the target network is desired; establishing a call to the mobile subscriber unit in the target network using the second identification number; and connecting, at the predetermined node, the mobile subscriber unit and the second party.