Method of call transfer between wireless local area networks connected to a mobile network, and associated management device

A device for managing call transfer between first and second wireless local area networks using a wireless access technology and respective first and second secure gateways connected to a core network of a network offering packet-switched services, for a mobile communication terminal including at least one layer 2 interface adapted, in the event of activation, to control transfers between wireless local area networks, which device comprises i) detection means adapted, in the event of setting up of a call between said mobile terminal and said core network via a first secure tunnel set up within said first wireless local area network between said mobile terminal and said first secure gateway and associated with authentication and security data, to generate a warning message if said mobile terminal enters an area of intersection between radio coverage areas of said first and second wireless local area networks, and ii) management means adapted, in the event of reception of a warning message, to trigger a procedure of pre-authentication of said mobile terminal, at the level of an IP layer, vis à vis said second security gateway, via said layer 2 interface and said first secure tunnel, and with said authentication and security data, then to instruct the setting up of a second secure tunnel between said mobile terminal and said second security gateway, updating of mobility management information via the second secure tunnel, and activation of said layer 2 interface so that it proceeds to the transfer between said first and second wireless local area networks by sending said second security gateway, via said second secure tunnel, a peer address updating message in respect of the mobile terminal, then to authorize the call to continue via said second secure tunnel when said transfer has been completed.