Abstract: An extension telephone having a numeric keypad for entering inputs including programming data is connected to a cellular line access unit via an I/O connector. The cellular line access unit, which includes a processor and a memory, stores programming data received from the extension telephone within the memory and accesses the programming data in the memory to establish communication between the extension telephone and a cellular communication network. In a preferred embodiment, programming data that is input utilizing the keypad of the extension telephone is transmitted to the cellular line access unit as a series of dual tone multi-frequency (DTMF) signals, and the cellular line access unit provides feedback in response to the programming data, for example, by generating a tone or displaying a message within a display of the extension telephone.