Provision of cellular/wire-line service

Apparatus and a method for providing roaming service to a telecommunications station which can act as a cellular station or if plugged into a jack connected to a land-line switch, can act like a land-line telephone. When such a Universal Main Station (UMS) is plugged into a jack connected to a land-line switch, the station calls a server system which obtains the directory number corresponding to the jack into which the UMS was plugged. The server notifies a home switch of said UMS to forward calls to that directory number. When the UMS subsequently unplugs from the jack, the UMS registers as a mobile station and the home switch is notified to forward calls to the UMS, acting as a mobile station and identified by a secret directory number, identified in the course of the registration. Advantageously, this arrangement allows a mobile station equipped with an arrangement for detecting the presence of land-line power and arranged to substitute signals received from a jack for radio signals to roam widely, and to receive a choice of cellular service or land-line service wherever the station roams.