A telephone, or phone, is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be heard directly. A telephone converts sound, typically and most efficiently the human voice, into electronic signals that are transmitted via cables and other communication channels to another telephone which reproduces the sound to the receiving user.

In the Left Behind series, telephone communication was initially mostly through landlines, with consumer-grade cellphones introduced sometime during the Tribulation as the Global Community set up telecommunications towers throughout the world. During the Millennial Kingdom, cellphone implant technology was made available to those seeking to carry a mobile phone on them that they could access instantly.