The Packetized Ensemble Protocol (PEP) is a protocol

Communications protocol

A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications...

 used by Telebit

Telebit

Telebit was a US-based modem manufacturer, most notable for their TrailBlazer series of high-speed modems. One of the first modems to routinely exceed 9600 bit/s speeds, the TrailBlazer used a proprietary modulation scheme that proved highly resilient to interference, earning the product an almost...

 modem

Modem

A modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...

s. It uses the full bandwidth

Bandwidth (computing)

In computer networking and computer science, bandwidth, network bandwidth, data bandwidth, or digital bandwidth is a measure of available or consumed data communication resources expressed in bits/second or multiples of it .Note that in textbooks on wireless communications, modem data transmission,...

 (3000 Hz) of the telephone line

Telephone line

A telephone line or telephone circuit is a single-user circuit on a telephone communication system...

s and dividing it in hundreds of channels. The modem only chooses the channels that are error free, which makes PEP usable on bad lines. The disadvantage is the relatively long time it takes to switch between sending and receiving data.