A parking area entrance or exit barrier includes a control system which receives inputs from various accessories associated with the operation of the barrier, and which provides control signals to the various accessories of the barrier. Communications from the master to the remote units are encoded in loop current fluctuations, whereas communications from any remote to the master unit are encoded in loop voltage fluctuations. Device information, which indicates the type of subscriber data that the first telecommunications device is configured to process, is then sent from a first to a second telecommunications device.