HISTORY OF TELEPRINTER INTRODUCTION
INTO THE UK

The early days of Telegraphy involved a large number of people moving paper and operating various transmitting and receiving apparatus.  Morse code knowledge was required and the machines required in depth training.

In the late 1920's the Teleprinter appeared on the scene which had a keyboard similar to a typewriter, which meant less technical individuals could use the machine.  Another feature of the Teleprinter was that it could auto start and stop without operator assistance.

Teleprinters would firstly only be used on point to point circuits due to their use of DC signalling. This was a problem because it meant that the telephone system could not be utilised for Telegraph traffic.

The introduction of the multi-channel voice frequency (v.f.) working in the telegraph system, in 1931, allowed Teleprinters to transmit long distances.  Ancillary equipment was used to convert the DC signalling to voice frequency signalling.

In 1932 Telex was introduced and this allowed a customer to have a Teleprinter on their premises and the ability to dial another teleprinter via the telephone network and then transmit from machine to machine.  They could also connect to the GPO Printergram service, which was a Teleprinter service base on the Phonogram.  All this required v.f. ancillary equipment.

The service was originally operated on a frequency of 300 cycles per sec, but a change-over to 1,500 cycles per sec. was made in the latter part of 1936 in order to line up with international agreement and to secure advantages which the higher frequency has over the lower.

By 1938 there were about 380 teleprinter installations in the UK and the associated "printergram" service, necessitated the handling of an average of 7500 incoming and 20,000 outgoing messages per week at the 32 printergram positions in the Central Telegraph Office.

The GPO was investigating issues with the v.f. working and the decision was made to segregate the Telephone and Telegraph cable  networks. Automatic working was also going to be introduced but World War two put a stop to that and the GPO used a network of special telegraph switchboards to connect calls.  This system operated in a similar fashion to the old manual exchanges, which were all operator controlled.

30th August 1958 saw the introduction of a fully automatic telegraph exchange in the UK, based in Strowger switching.  No ancillary apparatus was required as the system used DC signalling throughout the local networks.  Roll out to automatic working was completed by 1960.

All the Strowger Telex exchanges were closed by the summer of 1992.

BT introduced Stored Program Control exchanges to replace the Strowger exchanges but these only lasted until 2008 when BT officially discontinued all it's telex services in the UK.

Last revised: February 21, 2026