Dial Identification

All the British GPO dials have a number on the rear - generally on the outer rim of the dial. e.g. E10/35 235 - This means it is a Dial No. 10 made by Ericsson in 1935.  The 235 is a mark number which shows the modification status of the dial.

In the UK many manufacturers made dials and these generally have little or no markings.

GEC dials generally have a stamping on the dial finger plate or finger stop advising of the Patent number.  A number may be found under the dial outer rim.

British Ericsson dials will have apart number on them that is 4 figures prefixed by the letter "N".  Under the outer rim of the dial.

ATM dials were prefixed by the letter "T" and ATE by the letter "L".

For other dial identification please use the pictures below.

Pictures for identifying dials


Automatic Electric 'sunburst' dial, produced in Chicago before the 'Mercedes' pattern.  These were not used by the British Post Office but may have appeared on private automatic systems imported to Britain before 1910.


This is the Automatic Electric dial that was fitted to the original telephones used at Epsom and the Official Switch in London in 1912; it appears that early supplies had Chicago-made dials.  The UK-made ‘lookalike’ came soon afterwards, with the same ‘Mercedes Benz’ label clip and wording on the label.  Some of the British-made dials were in an oxidised bronze finish, whereas the American one were nickel-plated.  Similar dials were made in France as well and for repair purposes, all parts are interchangeable regardless of maker.  Known to collectors as the 'Mercedes' pattern.

The same thing but in colour!


A Dial No. 1 offered on eBay during 2003 - front and rear


'Mercedes' pattern dial manufactured in France by Thomson-Houston.


Dial made by Northern Electric in Canada under licence from Automatic Electric, similar to the 'Mercedes' pattern.

Dial No. 3, with Australian dial markings, from the front....

...and from the rear.

A less 'golden' image. The rear view - Dial made in 1920


Dial No. 3 - a British example.


Dial No. 8 - rear view


Automatic Electric type 23 dial, used in North America. This replaced the Mercedes pattern.
The similar-looking type 24C was made by Automatic Electric's British associate ATM Ltd as its model 24C.


ATM Dial No. 24 - front and rear
(Marked T4219 or L39298)


11-digit Automatic Electric dial used in the USA for special purposes.


Method of removing number ring on Automatic Electric dials when changing dial labels.


Dial fitted to many telephones used by KTAS, Denmark. It is in fact a BPO NO. 10, made by Siemens Brothers.


Hull Corporation Tele. 232, made by ATM Ltd and fitted with their Dial 24C.  The shape of the finger stop distinguishes the dial from a BPO No. 10. Hull was the only place in Britain where this pattern of dial was used on a public network, although many railway PABX telephones had them as well.  The design was never adopted by the BPO, however.

Close-up of Dial No. 24C fitted to a Portuguese telephone.

The same thing produced in India and applied to many modern reproduction telephones (repro pictured).


Number plate of a French type 24C dial made by Martens.  It is, how you say in English, rather worn and faded.


An early production Dial No. 10.  Some collectors assume all dials with small centre labels are No. 8 but this is not so.
Dial No. 8 has four terminals on the back, the No. 10 has five.


Siemens Brothers Dial No. 10 fitted to a 300-type telephone exported to Canada.
Note the letter O on digit 6 and the instructions for using the telephone.
This is on a magneto party line, with the option of 'simplex dialling' for making automatic calls.
Similar calling arrangements were made in some British coal mines.


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Last revised: November 30, 2021