Communication at a distance by electronics transmission of impulses, as by telegraph, cable, telephone, radio, or television constitutes telecommunication. Transmission of information is possible through co-axial cables, wireless media, Fiber optics. The basic components of telecom department can be stated as follows:

Radio System
EBTS(Enhance base transceiver system)
RCW (Radio Console Workstation)

FOTS( Fiber Optics Transmission System)
PIDS(Public Information Display System)/ PAS(Public Address System)

Master Clock
CCTV(Close Circuit Television)

Telephone system
CSS role & Function

NP SCADA( Non Power Supervisory Control And Data Acquisition)
UPS( Uninterrupted Power Supply)
Networking System

All of the above are parts of telecom department, All of them combine to form a highly efficient communication system and all of them are needed for smooth functioning of metro rail.