In an underground urban railway system, the efficient and reliable operation of the telecommunications is of paramount importance to the operation of the entire Metro system. Even though there are acceptable telecommunications systems for a wide range of application, only those systems that fulfill the highest standards of manufacture and the special requirements concerning the operation of the railway and the associated installations are suitable to be used in the Metro Base Project.
Moreover, the appropriate provisions have been made during the design and installation of the equipment in the extensions of lines 2 and 3, so that these systems are fully compatible with the already operating systems of the Base Project.

General Information
Automatic Telephone System	It consists of a telephone exchange system, whereto PRIMARY-ISDN type lines are connected, serving the wire communications needs.
Direct Telephone Line Personnel	Telephone sets for: Communication is cases of emergency and Maintenance Traction Power Removal devices
Direct Telephone Line	Telephone sets installed on the platforms
Radio communication	Wireless TETRA system:       1.  Maintenance       2.  Police       3.  Depot       4.  Radio communication consoles in the control center and the depots       5.  Radio communication consoles in the Cabs of new Trains       6.  Portable
Monitors for: Closed Circuit TV (CCTV)	Cameras in the Concourse and Platform areas, as well as in the Cash Counting Room Information Controller in the OCC Police in the OCC  Police for the protection of cash Station Masters Train Drivers Provision for Future Extensions
Public Address System (PA)	Announcements from: OCC Station Masters Platform Announcement Point Information Controller in the OC
Distribution System	Digital Management System Spare Fiber Optic Cable