Sorry for the late response.
With a UK operator I used to look at SS7 and PCM – Pulse Code Modulation – for E1.0 (2.048Mbits/s) systems. This was well before SDH. A Mux (Multiplexer) approach was
used to “step up” circuits to a higher bandwidth. This was the PDH “mux mountain”.
A time slot is a recurring interval of time. It is a property of a digital system.
For a E1.0 (2.048) PCM system that bandwidth is derived as follows:-
-Number of Time slots: 32 TS, or Timeslots
-Sampling rate: 8000Hz
Bandwidth is: 32 (TS) * 8000Hz * 8bits
Bandwith is: 2.048Mbits/s
Two time slots cannot be used. By convention, Time Slot 16 is “reserved” for Signalling. Time slot 0 is reserved for synchronisation and frame alignment. Therefore, this means that with a E1.0 TDM (Time Division) PCM system 30 Time Slots are used to convey Voice (speech) as a digital
VBR/ Wallis Dudhnath