A communications system and method for providing a cellular communications link between a user traveling on a mobile platform (or at a remote location) and a terrestrial based segment. The system and method uses a radio access segment located on board the mobile platform (or at the remote location) to interface with the user's personal communications device. The bearer terminal facilitates the transmission of information to and from the radio access segment, via an off-platform system, to the terrestrial segment. The terrestrial segment manages the communications link between one or more cellular service providers who are accessing the terrestrial segment and the mobile platform (or a remote site). The system does not limit access to the terrestrial segment to only one cellular service provider but instead allows virtually any number of cellular service providers to access the terrestrial segment and to participate in providing a cellular link to the mobile platform (or a remote site).