For a communication terminal (10), proposed is a security module (1) configured to authenticate a telecommunications network (2). The security module (1) comprises a locking module (12), for disabling usability of an application module (11), an unlocking module (13), for re-enabling usability of the application module (11), and a control module (14) for activating the unlocking module (13), depending on received data that is assignable in an authenticated way to a specific telecommunications network (2). The control module (14) is configured to activate the locking module (12) depending on the selection and usage of the application module (11). The control module (14) is configured to activate the unlocking module (12) depending on the reception of authorization messages, that can be authenticated, or authentication data of the telecommunications network (2). By disabling and re-enabling usability of the application module (11), depending on received data that is assignable in an authenticated way to a specific telecommunications network (2), the usage of network independent applications can be tied to the usage of a specific telecommunications network.