© 2008 Museum of Communication

In the beginning connections between telephones were made manually, by operators working at switchboards located in central switching offices. Shown below are a 10-Line Domestic Exchange dating from 1910, which was probably used in a large house to communicate with the staff, and a 5-Line Intercom and Extension from 1916. This equipment was originally installed in the Headmaster's office in Tollcross School Edinburgh, with extensions in five classrooms and remained in use until the 1970's. There is also a further example (1911 GEC Intercom 'calling' exchange 4-lines, Ex Tollcross School)

Originally, telephone exchanges were manually operated: the subscriber called the exchange operator, who made the connection to the required number. Strowger's experiments resulted in the Automatic Strowger Exchange. This electro-magnetic exchange is based on an ingenious design of a rotating switch with any number of contacts - one for each line. For over a century "Strowger Exchanges" were used throughout the world, although most countries have now replaced them with more modern systems; in Britain, the totally electronic "System X" was adopted.

A further example of a telephone exchange system is our Merlin Monarch Call Connect System from the 1980s (donated to us by the Scottish Tourist Board).