* DS = Digital Stream, Digital Signal
Signal---------Rate---------Structure-----Number of DS0s
DS0-----------64 kbps-------Time slot---------1
DS1--------1.544 Mbps-------24 x DS0---------24
DS1c-----------3 Mbps--------2 x DS1---------48
DS2------------6 Mbps--------2 x DS1c--------96
DS3-------44.736 Mbps--------7 x DS2--------672
* T spec
T1 = 1.544 Mbps (DS0 x 24)
T2 = 6.312 Mbps (T1 x 4)
T3 = 44.736 Mbps (T2 x 7)
T4 = 274.176 Mbps (T3 x 6)
* E spec
E1 = 2.048 Mbps (DS0 x 32)
E2 = 8.448 Mbps (E1 x 4)
E3 = 34.368 Mbps (E2 x 4)
E4 = 139.264 Mbps (E3 x 4)
E5 = 565.148Mbps (E4 x 4)
