A method for providing a data connection between a mobile terminal and a first core network of a first cellular network of the first cellular network, the mobile terminal comprising a processing unit, a memory unit, and a first authentication module and a second authentication module, wherein the first authentication module comprises a first user profile with first authentication information for access to the first cellular network, wherein the second authentication module comprises a second user profile with second authentication information for access to a second cellular network, wherein the process comprises the following steps: Establishing the data connection using an access network of the second cellular network using the second authentication information, Transmission of at least parts of the first authentication information to the first core network via the access network of the second cellular network, Authentication of the first user profile at the first core network, in particular at the first core network of the first cellular network, using the at least parts of the first authentication information; Providing the data connection using the transmitted first authentication information, characterized in that the mobile terminal comprises a cellular-to-WiFi converter that enables a first-user-profile-like data transmission with the second cellular network, wherein the second authentication module is connected to a cellular communication interface of the cellular-to-WiFi converter, and wherein the first authentication module and the memory unit are connected to cellular communication interface of the cellular-to-WiFi converter. wherein the first authentication module comprises a first user profile with first authentication information for access to the first cellular network, wherein the second authentication module comprises a second user profile with second authentication information for access to a second cellular network, wherein the process comprises the following steps: Establishing the data connection using an access network of the second cellular network using the second authentication information, Transmission of at least parts of the first authentication information to the first core network via the access network of the second cellular network, Authentication of the first user profile at the first core network, in particular at the first core network of the first cellular network, using the at least parts of the first authentication information; Providing the data connection using the transmitted first authentication information, characterized in that the mobile terminal comprises a cellular-to-WiFi converter that enables a first-user-profile-like data transmission with the second cellular network, wherein the second authentication module is connected to a cellular communication interface of the cellular-to-WiFi converter, and wherein the first authentication module and the memory unit are connected to cellular communication interface of the cellular-to-WiFi converter. Establishing the data connection using an access network of the second cellular network using the second authentication information, Transmission of at least parts of the first authentication information to the first core network via the access network of the second cellular network, Authentication of the first user profile at the first core network, in particular at the first core network of the first cellular network, using the at least parts of the first authentication information; Providing the data connection using the transmitted first authentication information, characterized in that the mobile terminal comprises a cellular-to-WiFi converter that enables a first-user-profile-like data transmission with the second cellular network, wherein the second authentication module is connected to a cellular communication interface of the cellular-to-WiFi converter, and wherein the first authentication module and the memory unit are connected to cellular communication interface of the cellular-to-WiFi converter.