Digital Signal Designation

Digital Signal Designation is the classification of digital bit rates in the digital multiplex hierarchy used in transport of signals from one location to another in telecommunications.

The DS technically refers to the rate and format of the signal, while the T designation refers to the equipment providing the signals. In practice, "DS" and "T" are used synonymously; for example, DS1 and T1, DS3 and T3. ^[1]

Digital signal line rates

North America

Digital Signal Designation	Bandwidth/data rate	Channels (DS0s)	Carrier designation
DS0	64 kbit/s	1
DS1	1.544 Mbit/s	24	T1
DS1	3.152 Mbit/s	48	T1c
DS2	6.312 Mbit/s	96	T2
DS3	44.736 Mbit/s	672	T3
DS4	274.176 Mbit/s	4032	T4
DS5	400.352 Mbit/s	5760	T5

^[2][3]

Europe

Digital Signal Designation	Bandwidth/data rate	Channels (SL0s)	Carrier designation
Signal Level 0	64 kbit/s	1
SL1	2.048 Mbit/s	30	E1
SL2	8.448 Mbit/s	120	E2
SL3	34.368 Mbit/s	480	E3
SL4	139.264 Mbit/s	1920	E4
SL5	565.148 Mbit/s	7680	E5

Optical carrier

See SONET for more information.