A cell phone registers with the nearest cell tower and establishes communications with it, so that when a call comes in for you, the system knows which cell tower to relay the call to on its way to your handset. Without this arrangement, the cell phone company would have no way of getting a call routed to you. I programmed the scanner to monitor the frequency of the cell tower nearest to Teltec, so it would pick up information from the tower identifying the phone number of every cell phone in or even just passing through the area.