The
T-carrier is a member of the series of
carrier systems developed by AT&T
Bell Laboratories for
digital transmission of multiplexed
telephone calls. The first version, the Transmission System 1 (T-1), was introduced in 1962 in the
Bell System, and could transmit up to 24 telephone calls simultaneously over a single transmission line of copper wire. Subsequent specifications carried multiples of the basic T1 (1.544 Mbit/s) data rates, such as T2 (6.312 Mbit/s) with 96 channels, T3 (44.736 Mbit/s) with 672 channels, and others.