Australian Post Office
Telephone No. 400

The 400 series telephone was developed by the PMG in 1957 and introduced into service in 1958 to replace the 300 Series telephones. This telephone series was based on the Ericsson/GEC 1000 type and designed to work on longer and lighter gauge cables (1000 ohm lines). It was fitted with a new 5 winding Induction Coil (Coil, Induction No. 21A), had a more efficient anti-sidetone circuit, a sensitive rocking armature receiver and a new style handset with no spittoon. 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 table and wall models. The 410 was used on Shared Service.

Initially it was intended that the 400 Series would be available in a range of colours but due to fading issues 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 Telephone 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 GEC/Ericsson 1000 shape case as the new 400 series but the production models had the older 300 type case. The ivory 400 series was only available as a table model and was made by Ericsson. The wall models were only made by AWA.

The 400 type was very similar to the BPO prototype, the Telephone No. 700. This phone was field trialled for the UK but was not used by the BPO probably due to the new plastic cased Telephone No. 706 that was being developed at that time, which was then introduced in 1959.

Ericsson produced some of the the 400 series telephones for the APO:-
400 - 400AT, 400AW and 400MT.
401 - CE11020 - Ericsson N1035A, produced by AWA and STC - 300 case with 1000 handset - no vents in base plate.
402 - CE11020 - Ericsson N1390A - 300 case with 1000 handset.
403 - CE11021 - Ericsson N2127 - complete with generator which is located above the centre on the escutcheon plate.
403 - CE11024 - complete with generator which is central in the escutcheon plate.
404 - CE11022 - Ericsson N1035A - 300 case with 1000 handset and press button.
405 and 411 - CE11022 - Ericsson N1035A - 300 case with 1000 handset - Also known as the APO 400CBT.
406 and 407 - CE11022 - Ericsson N1390A - 300 case with 1000 handset - Ivory.
408 - CE11021 - complete with generator - Ivory.
409 - CE11021 - complete with generator - Ivory.
410 - CE11023 - Ericsson N1036A - 300 case with 1000 handset - Also known as the APO 400ADT & 400CBDT - Shared Service.
411 - 300 case with 1000 handset - no press button - vents in base plate and case (ATM model L11709A1).
415 - CE11024 - complete with generator and connected by plug and socket.
418 - Wall phone with dial.
419 - 300 case with 1000 handset - one press button - round vents in base.
420 - 300 case with 1000 handset - one press button

401, 402, 404, 405, 406, 407 AT & CBT - CE11022 - when wired to a Socket No. 610 with a Plug No. 603.

.All Ericsson drawings are dated 1957.

The manufacturer can also be sometimes identified by the part numbers on the internal components. Number prefixed with an "L" would be ATM/ATE, those with an "N" prefix will be ETL and those with "C" on them will be GEC.

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.

British Ericsson (ETL) Cross reference

Ericsson No.	Australian Post Office Telephone No. No.	Colour	Information
N1035A	401AT	BLACK	NO HANDLE
N1390A	402CBT	BLACK	NO HANDLE
N2127A1	403MT	BLACK	NO HANDLE
N2127A4	403MT	BLACK	NO HANDLE
N1035A1	404AT	IVORY	NO HANDLE
N1035A5	404AT	IVORY	NO HANDLE
N1035A7	404AT	IVORY	NO HANDLE
N1035A2	405AP	IVORY	HANDLE
N1390A3	406CBT	IVORY	NO HANDLE & INSECT PROOF
N1390A1	406AT	IVORY	NO HANDLE
N1390A2	407CBP	IVORY	HANDLE
N2127A5	408MT	IVORY	NO HANDLE
N2127A2	408MT	IVORY	NO HANDLE
N2127A3	409MP	IVORY	HANDLE
N1035A6	411AT	BLACK	NO HANDLE
N1035A3	411AT	BLACK	NO HANDLE
N1035A4	411AT	BLACK	NO HANDLE