scope:

This instruction applies to all staff engaged in the maintenance and testing of discrete telephone instruments (including point to point and Omnibus type phones) used for operational purposes on the operating floors within Network Rail's Operational buildings which are provided primarily to facilitate safety critical communications for the safe operation of the railway.

For the purposes of this instruction an operational building shall include manned buildings such as Control Offices, Signalling Centres including Signal Boxes, Gate Boxes and Crossing Keepers Huts, and Electrical Control Offices etc but excludes non-operational rooms situated in operational buildings such as messrooms, relay rooms etc.

It does not cover telephone instrucments situated within unmanned buildings such as Track Section Cabins, Feeder Stations, and Relay Rooms etc.

Nor does it apply to Network Rail telephones located externally on the lineside or PETS units within signal boxes and control rooms or telephones handsets / instruments attached to or forming part of a concentrator system.

Purpose

This telecoms maintenance instruction defines the maintenance and functional testing that Network Rail require for their telephones used in operational buildings.

The purpose of maintaining and testing these telephones is to decrease the incidence of failures through deterioration and to identify potential failures before they become service affecting.