Phone line interface
receives and sends telephone signals through the phone line Radio - amplifies signals to and from phone-line interface, user controls and speaker phone (if present) and broadcasts and receives radio signals to and from the handset Power - supplies low voltage power to the circuits and recharges the battery of the handset
Phone Line Interface
Phone line interface components do two things. First, they send the ringer signal to the bell (if it's on the base) or to the radio components for broadcast to the handset. This lets you know that you have an incoming call. Second, they receive and send small changes in the phone line's electrical current to and from the radio components of the base. When you talk, you cause small changes in the electrical current of the phone line, and these changes get sent to your caller. The same happens when the caller talks to you.