Manufacturer codes were allocated by the British Post Office (BPO) and are found both on instruments made for the BPO and on othes. These are the most commonly found codes and, when followed by two digits, this number indicates the year of manufacture. Australian manufacturers also used this system.

All BPO telephone sets (and piece parts) carried a pattern number, in which table telephons, portable telphones and piece parts such as handsets carried even numbers whilst wall phones had odd numbers. Special and experimental telephones had numbers perfixed SA (Special Apparatus), whilst designs inherited from the former National Telephone Company were prefixed NT. The pattern is often followed by a mark number, generally starting with mark 234, which would be equivalent to Mk 1, 235 = Mk 2, etc., in any other organisation's series.

The first and second letters in the code identify the company while the third letter in the code can indicate the town or city where the manufacture took place.

Wooden wall sets and bell sets code markings. Number 11 telephone E = British Ericsson, 25 = the year 1925. Mark No. 5, the fifth version of this item.	11 E 25 238
164 and 184 handset code markings on the handgrip. S = Siemens, 34 = 1934. General Post Office, 164 = Handset type for 3 wire cord (note). Mark No. 1, the first version of this item.	S34 GPO 164 234
Note: 164 handset - where one side of the transmitter and one side of the receiver use a common wire in the circuit. 184 handset - where a 4 wire cord is used and the transmitter and receiver are in separate circuits.

The British Post Office (BPO) purchased telephones and other apparatus from various manufacturers. On a lot of equipment the manufacturer can be identified by the use of the manufacrurer's code.

Where a PO factory code is shown, this means that the equipment has been made or refurbished by one of the BPO factories. Quite often these codes are on labels stuck over the top of the original manufacturer's code. At present these are still a "grey area" and not necessarily correct!

A very useful website for further information and updates on this list is the Bob Freshwater site. There is a lot of information about telephones and related equipment. Go to http://web.ukonline.co.uk/freshwater/

CODE	MANUFACTURER	CODE	MANUFACTURER
A9W	Trench & Manhole Covers Ltd	AAG	Mullards Ltd - London SW18
ACL	Advance Electronics Ltd. Hainhalt, Middx.	ACW	AVO Ltd - London SW1
AEI	Australian Electrical Industries	AEK	GEC-AEI Telecommunications, Kirkaldy, Fife, Scotland
AEG	GEC Telecommunications, Glenross, Scotland.	AEP	Automatic Electrical, Portugal
AEI	AEI Telecomms Group - Worsley Bridge Rd, London, SE26	AK	Peel-Connor Telephone Works Ltd - became GEC
AKA	Sterling Telephone & Electrical Co - Dagenham, Essex	ANS	Ansaphone Ltd - Camberley, Surrey
AP	Admiralty Pattern (British Navy)	ASW	Armstrong Stevens & sons - Willenhall, Staffs
ATE	Automatic Telephone and Electric	ATL	Austin Taylor Electrical Ltd - Bangor, North Wales
ATK	Plessey Telecom Group - Kirby Ind. Estate, Liverpool	ATW	Automatic Telephone & Electrical Co. Ltd - Wigan, Lancs
AUC	Unknown	AWA	Amalgamated Wireless Australia (AWA)
AXA	White, H & Co - Yarmouth	B2P	Inventec Electronics - Malaysia
BBK	Bakelite Ltd - Birmingham	BCL	Bratt Colbran Ltd
BDA	Unknown	BDB	W T Henley's Telegraph Works Co. Ltd - London (became AEI)
BEB	Callenders Cable & Construction Ltd - London E16 (previously BE)	BLD	Birby's Ltd - Liversedge, York
BSD	Mullard Radio Valve Co - Mitcham, Surrey	BUL	Bullers Ltd - Stoke on Trent
C	General Electric Co - Coventry (later GEC)	CCA	Carron Co (previously CC)
CCB	Creed & Co Ltd - Brighton, Surrey	CCD	Creed & Co Ltd - Croydon, Surrey
CSB	E S Gurnett	CTP	Creed & Co Ltd - Pontypridd, Glanmorgan
CWL	Pye Telecommunications - Cambridge	CYA	Marconi Co Ltd - Chelmsford, Essex
DAE	A P Beeson Ltd - Hove, Sussex	DAW	Duct & Access Covers PLC - Wales
DBA	John Gell Ltd	DBK	Bakelite Ltd - Durham
DCA	Synchronome Co Ltd - Wembley, Middx	DEA	Muirhead & Co - Bekenham, Kent
DEK	Dover Engineering Co - Dover, Kent	DFM	Denis Ferranti Meters Ltd - Bangor, North Wales
DJA	Telegraph Construction & Maintenance Co - London SE10 (see S & SEG)	DZA	Relay Automatic Telephone Co
E	British Ericsson - later Plessey, then GPT and then Siemens	EEC	Elliott Ltd - West Midlands
EET	Plessey - Beetson, Notts (formerly Ericsson, see E)	EEX	Plessey - Sunderland (formerly Ericsson)
EHA	Cambridge Instrument Co - London SW1	EMI	EMI (Valve Division) - Ruislip, Middx
ENA	British Time Recorder Ltd - London EC1 (previously EN)	ETL	Ericsson Telephones Ltd
FB	GPO Factory, Birmingham	FBR	GPO Factory, Fordrougth Lane, Birmingham (refurbish)
FEL	Fidility Ltd (see FID)	FEN	Unknown
FGB	Sontronic ltd - Edgware, Middx	FH	GPO Factory - Holloway
FHA	GPO Factory - Holloway, London (assembly)	FHB	GPO Factory - Holloway, London (construction)
FHR	GPO Factory - Holloway, London (refurbish)	FID	Fidelity Radio Ltd (see FH)
FMC	Caine Electronics - Caine	FNB	GPO Factory - Edinburgh (construction)
FNR	GPO Factory - Edinburgh (refurbish)	FRA	Ferranti Ltd - Hollingwood
FRG	Unknown	FW	GPO Factory - Wales (Cwmcarn)
FWG	STC Consumer Electronics - Cwmcarn (formerly BT)	FWR	GPO Factory - Cwmcarn, Wales (refurbish)
G	General Electric Co (GEC) - see C	GAB	Greenwood and Butler - Leeds
GEC	GEC Telephones - Coventry	GEG	Osram Lamps and Lighting Co Ltd - Gateshead Co, Durham
GEL	GEC-AEI Telecoms - Accrington, Lancs	GEN	GEC-AEI Telecommunications - Newton Aycliffe, County Durham
GEP	GEC Telecoms Ltd - Treforest, Pontypridd	GKT	GKN PLC - Telford, Shropshire
GTE	Ferranti	H	Automatic Telephone & Electric Co (ATE) (formerly ATM, H stands for Helsby)
HA	Hall Telephone Accessories Ltd (later HAS)	HAA	Automatic Telephone & Electric Co - Liverpool (later Plessey)
HAS	Hall Telephone Accessories Ltd (formerly HA)	HCA	BICC Cables - Warrington
HCC	BICC - Liverpool (ex Helsby Cables)	HCL	BICC - Leigh (ex Helsby Cables)
HCP	BICC - Prescot (ex Helsby Cables)	HDL	Hudson's Electrical Devices Ltd - London SW2
HND	Highton & Sons - Dalston, London E8	HVA	Plessey Hivac Division - Ruislip, Middx (ex Hivac Ltd)
I	Ibex - London (later IBX)	IBX	Ibex Telephones - Harrow, London (formerly I)
IMP	Imperial Typewriter Co	JEK	Unknown
JKA	Brooker and Jackson Ltd - London N1	JX	Julius Sax & Co Ltd
JXA	Julius Sax & Co Ltd	KB	K E Beswick - Frome, Somerset
KEC	E K Cole Ltd - Rochford, Essex (later Ekco Avionics)	KKA	E K Cole Ltd - Southend, Essex
KNE	K & N Electronics Co Ltd - Maidenhead, Berks	KRN	Krone - Cheltenham
LDA	Cossor Communications Co Ltd - Stannore, Middx	LEA	Litholite Mouldings Ltd - Leicester (ex Watford)
LEB	Elliott Bros (London) Ltd - London SE13 (previously L)	LER	Lero Engineering Co - Coventry
LF	Lion Foundry - Kirkintilloch, Glasgow (later LFA)	LJS	Lustraphone Ltd
LWA	Lightwood & Son - Birmingham	M	P O Factory, St Johns Road, Dublin
McK&H	McKenzie and Holland (Australia)	MF	Walter Macfarlane & Co - Glasgow (later MFA)
MOV	M O Valve Co Ltd - London W6	MRL	McMichael Ltd
MS	McDowell Steven & Co - Falkirk (later MSL)	MTW	Modern Telephones Ltd - London SW19
MTJO	Mullard Ltd - London WC1	MM	Murphy Radio Ltd - Welwyn Garden City, Herts
MWB	Marconi Wireless Telegraph Co - Basildon, Essex	MXB	Motorola - Basingstoke, Herts
OE	Unknown	OAA	Gent & Co - Leicester (previously O)
PA	Unknown	PCB	Plessey - Whiteside Works, Bathgate, West Lothian (see PLF)
PEH	Pye - Hastings	PER	Plessey Electrical Equipment Divn - Romford, Essex
PGH	Pirelli - Eastleigh, Hants	PGL	Pirelli - Southampton
PL	Plessey - Ilford, Essex (later PLA)	PLA	Plessey - Ilford, Essex
PLF	Plessey - Whiteside Works, Bathgate, West Lothian	PLP	Unknown
PLS	Plessey - Kemberry Rd, Swindon, Wilts	PLV	Plessey - Havant, Hants
PLW	Plessey - Chaney Manor, Swindon, Wilts	PLX	Plessey - Newport, Gwent
PMC	ATE Wigan Ltd - Pioneer Works, Wigan, Lancs (see PML)	PML	ATE Ltd - Chorley, Lancs
PSD	Plessey - Dublin, Ireland	PSL	Poulton Selfe & Lee Ltd - Wickford, Essex
PTE	Pye Telecoms Ltd - Ekco Works, Southend, Essex (see KKA)	PTL	Pye Telecoms Ltd - Haverhill, Suffolk
PM	Reliance Telephone Co Ltd - Birmingham	PUJ	Plessey - Upminster, Essex
PWM	Postal Workshops Melbourne, Australian PMG	PX	Phoenix Telephones & Electrical Ltd - London NW9 (later PXA)
PXA	Phoenix Telephones & Electrical Ltd - London NW9 (formerly PX)	PYE	Pye Telecoms Ltd - Cambridge (see CWL)
PYI	Pye Radio Ltd - Cambridge	PYL	Pye Radio Ltd - Leicester
PYT	Plessey - Taplow, Maidenhead, Berks	RAA	Llandis & Gyr (formerly Aeronautical & General)
RAW	Roberts & Armstrong (Engineers) Ltd - Wembley, Middx	RBA	Reid Brothers (same as W Reid & Co?)
RIA	Rathdown Industries Ltd - Ascot, Berks	RLA	Ryford Ltd - Aldridge, Staffs
RLE	Ripaults Ltd - Enfield, Middx	RML	Rotheroe & Mitchell Ltd - Greenford, Middx
RNA	Radio, Phonopore & Electricals Ltd (Sterling took over)	RTL	Racal Transcom Ltd - Salisbury, Wilts
RTN	Reliance Telephone Co Ltd - Birmingham	S	Siemens Bros - Woolwich, London SE15 (later SEG)
SB&Co	Siemens Brothers and Company	SA	Denotes Special Apparatus on BPO instruments
SBD	Stonebridge Electrical Co Ltd	SBM	Salford Electrical Instruments - Manchester
SEA	Siemens Edison Swan - London N17 (became AEI)	SEC	Salford Electrical Instruments - Heywood, Lancs (part of GEC)
SEG	AEI Ltd - Woolwich, London SE18 (ex Siemens, see S)	SER	AEI Ltd - West Hartlepool, County Durham (ex Siemens)
SEW	Siemens Edison Swan - Woolwich, London SE15 (see SEA)	SUR	Siemens Halske - Germany
SID	Salmon Industries Ltd - Northern Ireland	SLW	Speke Telephones Ltd - Wilmslow, Middx (see SPK)
SPK	Plessey-Speke, Liverpool (ex Speke Telephones Ltd - see SLW)	SSA	Ebonestos Industries Ltd - London SE15 (previously SS)
SSG	Splintex Safety Glass Co - London W7	SSS	Smith's Industrial Instruments Ltd - London NW1
STC	STC - New Southgate, London N11	STE	STC (Valve Divn) - Paignton, Devon
STM	STC - Belfast, Northern Ireland	SUE	Submarine Cables Ltd - Erith, Kent
SUG	Submarine Cables Ltd - Greenwich, London SE3 (see DJA & S)	TBE	Telerelays Sales Ltd - Braintree, Essex
TCD	Telephone Cables Ltd - Dagenham, Essex	TCE	STC - Eniskillen, Northern Ireland
TCH	STC - Larne, Northern Ireland	TCON	Team Concepts International Ltd (Hong Kong)
TE	Telephone Manufacturing Company (formed in 1915, later TEA)	TEA	TMC - Dulwich, London SE21
TES	TMC - St Mary Cray, Kent (from 1939)	TEW	TMC - Winford, Cheshire
TGR	Thorn Ericsson - Rochester, Kent	TGW	Thorn Ericsson - Scunthorpe
TMA	TMC - Airdrie, Lanarkshire (see GNA)	TMC	Telephone Manufacturing Company (Australia)
TMK	TMC - King's Lynn, Norfolk	TM	TMC - Malmesbury, Wilts
TPC	TMC Transmission Divn - St Mary Cray, Kent	TR	Ernest Turner Electrical Instruments Ltd - High Wycombe (later TRA)
TRA	Ernest Turner Electrical Instruments Ltd - High Wycombe (formerly TR)	TSD	Telephone Supplies Ltd - Aycliff, County Durham
TTC	Taylor Tunnicliff & Co Ltd - Lastwood, Flanley, Staffs	TTH	TMC - Canterbury, Kent
TTL	TMC - Livingston, Bathgate, West Lothian (from 1969)	TYA	H Tinsley & Co
UAA	Walters Electrical Manufacturing Co Ltd - London (previously U)	UME	Multitone Ltd
VG	Evershed & Vignoies Ltd - London W4 (later VGA)	VGA	Evershed & Vignoies Ltd - London W4 (previously VG)
VLC	Varta Ltd - Crewkerne, Somerset	VTS	Venner Time Switches - New Malden, Surrey
W	STC - North Woolwich, London (Western Electric pre 1925, see WAA)	WAA	STC - North Woolwich, London E
WAB	STC - Newport, South Wales	WAE	STC - Basildon, Essex
WAS	STC - Southampton	WEA	Weatherlite Ltd
WER	Whiteley Electrical Radio - Mansfield, Notts	WI	Webb & Wells - Ilford, Essex
YA	British Army prefix	Z	Found as the first letter on most British Army items
ZA	Unknown	ZEA	Zenith Watch Co Ltd (GB) (previously ZE)
ZE	Zenith	.	.