Australian Post Office
The 400 Series telephone was developed by the PMG in 1957 and introduced into service in 1958 to replace the 300 Series telephones. The 400 Series was based on the Ericsson/GEC 1000 and was designed to work on longer and lighter gauge cables (1000 ohm lines). It was fitted with a more efficient anti-sidetone circuit and a sensitive rocking armature receiver. The 400 Series included automatic (401, 404, 405 and 411), central battery (402, 406 and 407) and local battery/magneto (403) versions and was made as both a table and wall telephone. The 410 was used on Shared Service.
Initially it was intended that the 400 Series would be available in a range of colours but only black and ivory were eventually available to subscribers. There were several variants of the 400 Series and they were manufactured by Ericsson and GEC in England and by AWA in Australia. The Ericsson/GEC version used an internal chassis like the Tele 332 or 332AT but the AWA version had all the main components mounted on a base plate. The initial APO instruction issued in 1958 showed the rounded Ericsson 1000 shape case as the new 400 Series but the production models had the older 300 type of case. The ivory 400 series was only available as a table model and was made by Ericsson. The wall model was made by AWA.
The GEC 400 type was actually the BPO prototype Telephone No. 700.
Ericsson produced some of the the 400 series telephones for the APO.
All Ericsson drawings are dated 1957.
This 400 Series was superseded by the plastic 800 Series in the 1960's but many, especially the 400MT, remained in service until the 1980's.
Source: PMG Technicians Handbook 1951
Extract from APO ETP0374 dated 1958
British Ericsson Cross reference
Last revised April 25, 2021