A mobile telecommunications network includes a radio access network comprising base stations and one or more additional access points. An access point is connected to a network core by an IP transport broadband connection. The access point is configured to appear to the mobile terminal as a conventional base station—that is, for example, it communicates with the mobile terminal using GSM or UMTS transport protocols and does not require any modification to a standard GSM or UMTS mobile terminal. Access Points may not be under the direct control of the network provider, and so are more susceptible to security threats. The described system allows the network provider to verify that the access point through which a mobile terminal is about to communicate is a legitimate and trusted base station and/or is at a particular location. Differential charging may be performed in dependence upon a subscriber's location.