Patent ID: 8879502

Claim:
A method for handing off a communication session of a user equipment from a first network to a second network, the method comprising; determining, by a network information server in the first network, whether an accessible base station of the second network is located in a vicinity of the user equipment based on information on a current location of the user equipment within the first network; generating, by the network information server in the first network, a trigger signal when the network information server determines the accessible base station of the second network is located in the vicinity of the user equipment; transmitting, by the network information server in the first network, the trigger signal to a call transmitting server; generating, by the call transmitting server, when the trigger signal is received, an activation call with a first telephone number as a caller number when the accessible base station of the second network is determined to be located in the vicinity of the user equipment; transmitting the generated activation call to the user equipment; initiating searching, by the user equipment in response to the generated activation call, for the accessible base station of the second network when the activation call with the first telephone number is received by the user equipment; and executing the handoff from the first network to the second network when the user equipment finds the accessible base station of the second network as a result of the searching and enters a service area of the accessible base station.