T1T1 is the name for a circuit that can carry any kind of digital information. A T1 circuit carries over 1.5 million bits of data per second, which makes T1 a pretty fast way to access the Internet.
T1 is sometimes called a "HiCap" by technicians. "Fractional T1" (or FT1) has been divided into 24 separate channels of 64,000 bps (bits per second). T1 runs on two pairs of copper wires; one pair for transmitting and one pair for receiving. ISDN and analog lines use only a single pair of copper wires.