GPO Telephones - House Exchange System

House Exchange System

The 300 series was much more than just the Tele. 332. There was a whole range of similarly designed products. Fieldsets (Tappers), Headsets, Pendant Telephones, Wall Phones and the House Exchange System. Many Private Telephone Companies had sprung up in the UK. As these were banned by law from connecting to external lines, they contented themselves with producing systems for automatically dialling between company offices, within the same building or, via private wires, rented from the GPO, virtually anywhere. The GPO could only do this via PMBXs (manual switchboards), ranging from the 2 to 5 line cordless boards, via the 25 and 50 line plug and cord boards to the mighty PMBX 1A, which, with its modular construction, could be any size a large company might require. The GPO regarded the Private Telephone Companies as a thorn in their flesh and a great loss of potential income. They decided to tap into this lucrative market. Initially they produced a system virtually identical to the competition and called it the House Telephone System. This appeared, from the rear, like a Tele. 332 but the front sloped down and was covered in two rows of buttons, by which a few other, similar, extensions could be called. Like the competition this system was entirely internal and could not connect to the PSTN (Public Service Telephone Network). Unlike the competition, however, the number of extensions which could be incorporated was strictly limited. The GPO tried again.

The 300 series House Exchange System, now known as the HES1, was a combination of the Tele. 332L and the House Telephone System. From both the front and rear elevations the instrument appeared as a normal 332L. From the side, however, it was a different story. The snout of the instrument had been stretched forwards a full 8 inches in order to mount 2 rows of call buttons, along with their plastic covered labels, forward of the switchooks. All stations could make and take external calls, call any other station and also transfer calls between them. For the first time, small companies did not need to employ a telephonist. A big selling point.