Phone maintenance equipment

GPO/BT (British Telecommunications) engineers leather tool bag containing:

A multi range meter 12D/1 with its original leather case,

test telephone 290 by Hosiden Besson ltd.,

two BT soldering irons with 50 v transformer,

one Weller 50v, 35 watt soldering iron,

two BT 50v 35w Elremco soldering iron c.1979.

A separate tool bag containing:

BT oscillator no. 87F

BT amplifier no. 109G

two headsets for line testing

a blue socket adapter

a yellow socket adapter

two soldering irons

A BT torch

GPO/BT no. 4 leather telephone engineer tool wallet case

This set of equipment was owned by an engineer, who used it to maintain council telephone lines and cables within the Royal Borough of Kensington and Chelsea. These lines were part of the Integrated Services Digital Network (ISDN), allowing for digital transmission through the analogue cables of the public switched telephone network (PSTN). From 1985, the ISDN enabled improved speeds on phone lines, and services such as videoconferencing, data services, and internet access. By the end of 2025, BT will turn off all PSTN and ISDN services, making a shift from analogue to digital telecommunication technology.