T-carrier

Left: A 66 block; center and right: Cabinets containing Smartjack network interface devices for T1 circuits.

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 (T1), 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.

Although a T2 was defined as part of AT&T's T-carrier system, which defined five levels, T1 through T5,[1] only the T1 and T3 were commonly in use.[2][1]

  1. ^ a b "T1 T2 T3 Speed Comparisons". 11 January 2020.
  2. ^ 1999 ad: On the left, in an aisle seat, a man who very much "filled" his airline seat while on the right side of the aisle is a height-challenged man whose shoe toes barely reach the floor "Is there a comfortable place between T1 and T3". Digital Link.