Foundation concepts: Network, Bandwidth.

Definition: T-Carrier is the generic name for digital high-speed data-transmission lines more specifically known in the United States as T-1, T-2, etc.

Overview

The basis of the T-Carrier system is the digital Channel, designated DS0 or T-0. A single DS0 channel has a capacity or Bandwidth of 64 kbps (64 000 bits per second), which is the amount of carrying capacity that Bell Labs originally defined as necessary to carry a digitized voice signal over their network. Originally, the name T-1 was used for a digital transmission channel with a bandwidth of 1544 kbps that carried 24 separate DS0 channels together with one 8 kbps channel for system-related information. Now the technology may be slightly different, and T-1 has become a less specific name for any 1544 kbps digital carrier. Similar names (T-2, T-3, etc.) are used for higher-bandwidth carriers:

1. a T-1 line is equivalent to 24 channels or 1.544 Mbps,

2. a T-2 line is equivalent to 96 channels or 6.312 Mbps,

3. a T-3 line is equivalent to 672 channels or 44.74 Mbps,

4. a T-4 line is equivalent to 4032 channels or 274.2 Mbps, and

5. a T-5 line is equivalent to 5760 channels or 400.3 Mbps.

although it is not common to hear of anything other than T-1 and T-3. In Japan, exactly the same system is used, except with the letter J instead of T. Originally T-lines were made of copper wire, and the designation FT was used for fiber optics, but now the distinction is often ignored.