BT GPO/ PO Gauges Tension Tool in case

BT GPO/ PO Gauges Tension Tool in a fitted brown leather 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.