Corresponds to DS-5 (Digital Signal Five), the fifth level in the North American T-carrier digital hierarchy. T5 was designed to operate at a signaling rate of 400.352 Mbps, which supports 5,760 DS-0 channels at 64 kbps. Little, if any, T5 was installed, and it is now considered obsolete, having been superseded by the SONET fiber optic transmission system (FOTS). See also channel, digital hierarchy, DS-0, DS4, FOTS, signaling rate, SONET, and T-carrier.