Digital Signal 1 (
DS1, sometimes
DS-1) is a
T-carrier signaling scheme devised by
Bell Labs. DS1 is a widely used standard in
telecommunications in the
United States and
Japan to transmit voice and data between devices.
E-carrier is used in place of T-carrier outside the United States, Japan, and South Korea. DS1 is the logical bit pattern used over a physical T1 line; however, the terms "DS1" and "T1" are often used interchangeably.