Patent ID: 7539309

Claim:
A method for automatic roaming between heterogeneous WLANs and/or GSM/GPRS/UMTS networks, comprising: requesting access, via a mobile IP node, to a WLAN at an access point, a basic service area of the WLAN including one or more access points assigned to an access server; authenticating, via a wireless interface within the basic service area of the WLAN, the mobile IP node requesting access to the WLAN; and transmitting from the mobile IP node, upon request from the access server, an IMSI stored on a SIM card of the mobile IP node to the access server, the IMSI of the mobile IP node being stored in a database of a SIM-RADIUS module, wherein, based on the IMSI, a logical IP data channel of the WLAN is user-specifically supplemented towards corresponding GSM data for signal and data channels of a GSM network by means of information stored in a SIM user database, by means of a SIM gateway module, to perform an authentication of the mobile IP node, necessary SS7/MAP functions are generated based on the GSM data, by means of the SIM user database and the SIM gateway module, the SIM-RADIUS module performs the authentication of the mobile IP node at an HLR or a VLR of the GSM network, based on the IMSI of the SIM card of the mobile IP node, with successful authentication, (1) an authorization of the mobile IP node is performed, a corresponding user profile based on the IMSI being downloaded at the HLR and/or VLR, (2) the mobile IP node receives a corresponding entry in a customer database of the access server, and (3) the WLAN is released for use by the mobile IP node, and the SIM-RADIUS module and SIM gateway module are located on an open network and have direct access to a plurality of GSM networks on the open network for authentication at an HLR or a VLR of each of the plurality of GSM networks.