With Solid Back Transmitter and exchange number label around the mouthpiece With Solid Back Transmitter housing but without the number label around the mouthpiece

Automatic Pedestal Telephone

Standard pedestal instrument for GPO Automatic exchange circuits.  Used with a Bellset, No. 1.

In 1924 the Telephone No. 150L was introduced, which superseded the Telephone No. 124.  Similar to earlier telephones in that it was a candlestick model, it was innovatory in introducing the dial to most subscribers for the first time.  Reflecting the progress of automatic switching, the dial operated the automatic exchange switching mechanism by sending out a series of electrical impulses corresponding to the number being dialled.

It was no longer necessary for the operator to connect all calls and provision was made for a dial.  Where a Telephone No. 150 was still connected to a manual exchange, the aperture in the base of the telephone for the dial was covered by a dummy insert (used as a number label holder) which could be replaced by a dial when the exchange was converted to automatic working.

When this telephone was introduced it used the Transmitter No. 1, to which was affixed the exchange number, and the dial blank plate was a Dial, Automatic, Dummy No. 2.  Around 1932 the Transmitter No. 22 replaced the Transmitter No. 1 and as there was no provision for the exchange number the Dial, Automatic, Dummy No. 4 was introduced, for C.B. telephones, which had a recess for a dial label.

The picture above shows the two styles of transmitter head which could be found on a Telephone No. 150.  To the left is the later style Bakelite 'Transmitter No. 22' which accepted the 'Transmitter Inset No. 10' which was superseded by the 'Transmitter Inset No. 13'.  The transmitter head to the right is the older style solid back 'Transmitter No. 1'.

The early type with the Transmitter No. 1 could have a Label No. 43 fitted between the speaking tube and the transmitter body.  This label advised of the Exchange name and number.

All models were fitted with Dial No. 10 and used with a Bellset No. 1 or 25.  Some of the early Dial No. 10's had a smaller dial label holder.

All models have no internal components except for switch hooks and the phone requires the correct Bellset to work properly (see above).  The switch hook springs in this telephone were totally insulated with no connection to the casing, which made the phone electrically safe.

The switch hook consists of three contacts that all make together. 

Many Telephones No. 150 were converted from Telephones No. 2 by the GPO.  These can be identified by the number 2 being crossed out and a number 150 stamped nearby on the top of the microphone swivel posts (see pictures below).

Early table telephones were connected to the internal wiring with a Strip, Flexible Cord Connection.  Click here for more information.

See also the Telephone Efficiency Committees Report on Common Battery Area telephones.

Model Use
Telephone No. 150 Supplied with a Dial, Auto, No. 10FA.  Supersedes Telephone, Nos. 72, 72A and 124.
Telephone No. 150B Supplied with a Dial, Auto, No. 10BA for use in the Brighton Area.
Telephone No. 150FA Supplied for use in Director Exchange areas.
Telephone No. 150L Originally for general use and then supplied in Non-director exchange areas.  Fitted with a Dial, Auto No. 10LA and Label No. 43C.
Telephone No. 150S Supplied with a Dial, Auto No. 10FS and superseded Telephones No's 82 and 124S. (Used on Siemens systems in Grimsby, Hurley, Ramsey, Southampton and Stockport areas).
Telephone No. 150W Supplied with a Dial, Auto No. 10FW and superseded Telephone No's 76, 82W and 124W (used on S.T. & C's  (late W.E. Co.) exchanges at Darlington and Dudley).

Telephone includes (1928):-
2 x Cords, Instrument No. 116.
1 x Cord, Instrument No. 222 waterproof.
1 x Cord, Instrument No. 302 waterproof.
1 x Cord, Instrument No. 504.
1 x Dial, Automatic No. 10....... (see table above)
1 x Hook, Receiver F.
1 x Transmitter No. 1.
1 x Receiver, Bell No. 1A.

Telephone includes (1946 and 1956):-
2 x Cords, Instrument No. 1/16E, Black 12".
1 x Cord, Instrument No. 2/22B, Brown, 33".
1 x Cord, Instrument No. 3/62B,  Brown, 72".
1 x Cord, Instrument No. 5/04E, (for Dials, Automatic only).
1 x Dial, Automatic No. 10 S.S., No. 10 ... or Dummy, No. 2 or No. 4.
1 x Hook, Receiver F.
1 x Transmitter No. 22.
1 x Receiver, Bell No. 1A.

Circuit diagram - N250.

Circuit diagrams - AT 1729 & CB 1403.

Paster Diagram - Click here.

Drawing - No. 9179.

Terminal Markings

TR   -
D   R

How to wire the Telephone No. 150 to make it work on Plug and Socket

Click here for pictures of a Candlestick before refurbishment

Click here for Candlestick construction and how to dismantle the phone

Candlestick construction

Candlestick Manufacturing (Messrs Keitmann)

How to convert to Plug and Socket

Collectors Information - what to look for

Telephone mouthpiece sanitisers

This is an early Telephone No. 150CB.
It has a dial blank called the Dial, Automatic, Dummy No. 2.
This had no recess for a number label.


Post 1932 Telephone No. 150CB.
It has a dial blank called the Dial, Automatic, Dummy No. 4.
This had a recess for a Label No. 160 on which was the exchange name and number.


Left hand side of swivel
This shows that the head came originally from a Telephone No. 72.  This was crossed out and it was then used on a Telephone No. 150.
Right hand side of swivel
This shows the manufacture code (H in this case), the year of manufacture (1920).
Right view Left view

Additional Information

This pillar-type telephone for central battery operation is the one familiar to nearly all collectors as the classic ‘candlestick’ telephone.  In Australia they are designated Types 38AT (automatic), 38MT (magneto) and 38CBT (central battery).  Reproductions of this telephone, made in some cases from the original tooling, are common and in Australia all piece parts are available separately.  Collectors may consequently encounter many convincing examples that are in fact made entirely or partly from reproduction parts.

Introduced in 1924, it was the PO’s first standard design of dial table telephone.  When the telephone was to be used on manual exchanges the space for the dial in the base of the telephone was covered by a dummy insert (used as a number label holder) that could be replaced by a dial when the exchange was converted to automatic operation.

Manufactured by: Ericsson, STC and others.

Colours: Black was the standard colour although subscribers could theoretically pay to have these telephones painted another colour (so long as they also paid to have them restored to black afterwards).

Variants:  In the early 1930's the solid-back microphones originally fitted were mostly replaced with a Bakelite moulding containing a standard carbon microphone inset (these assemblies were made by Siemens Brothers).  They were replaced because the later Transmitter was much more resilient to noise and transmission faintness.  In Australia these refurbished telephones were known as Type 138.

In consequence a telephone with its original solid back transmitter is relatively rare item.  This applies both in Britain and in New Zealand.  Ron Kay notes that some collectors there assume that their Western Electric style candlestick is a Siemens phone because the new replacement microphones have the name Siemens Brothers moulded on the Bakelite mouthpiece.  Similar modifications were also made in the USA, where the Bakelite replacements are known as ‘Bulldog transmitters’; some British collectors incorrectly use the name for the Siemens transmitters as well.

Question and answers on Candlesticks

Question: Should the Bakelite earpiece cap have a notch moulded on to the face and why is it there on some and not others?
"Earpieces No. 2" the correct earpiece  for a 'Receivers Bell No. 1A' and has the 'cutout' to hear the howler.  Other earpieces are either modern repro's or incorrect ones fitted years ago such as No's 5, 9, 13 or 14 etc most of which would fit but were really for use on other telephones i.e. Tele's 28, 80 etc.

Question: Why do some of the switch hook arms have solid plates and others hole cut in and what does the F stamp stand for?
Answer: Different manufacturers and the 'F' because they are "Hooks, Receiver F" - which is detachable hook (oxidised) for use with Receiver Bell No. 1A.  Used with 'Switches, Receiver No's 1, 2 and 3'.  The hole was also to save precious metal in the time of need, as we were close to or at war at that time. 

Question: Can anyone tell me what the original paint finish is on the stem and base of a Telephone No. 150?
Answer:  Enamel oven baked. The Stove enamel is believed to be mixed with a silica based paste and is probably too thick.

Question: Do you need to split the stem and the base?
Answer: That's how it was done in the factory but don't forget to HMP grease and cover the thread on the tube.  Don't refinish at all if you can avoid it.

Question: How do you remove the Bakelite grommet on the base in one piece?
Answer: Its not Bakelite, its a hard rubber compound.  Make a mandrill from wood or metal, gently warm with a hot air paint stripper and when it begins to smell push it through.  Refit with same heat and the ball of a ballpean hammer pressed from the inside.

Question: Should the Bakelite earpiece cap have a notch moulded on to the face and why is it there on some and not others?
Answer: Yes, it should for the reason of attracting the subscribers attention should they inadvertently leave the bell receiver on a flat surface.  A howler was connected to the line in the exchange hoping the noise would attract the customer.  The ones which were not notched and usually came with a set of small holes rather than one large one are  believed to be from private or non GPO systems.

Question: Is it possible to get replacement rubber rings for the base?
Answer: Google search of the internet might find 1/4 inch square or oval rubber as used in catapults.  USA is the land of the Inch now, other wise its metric.  7mm/8mm round black cord can also be purchased on Ebay. 

Question: What is the Bell Receiver coated with?
Answer: The Bell Receiver coating is made of "Pellolit" or Ebonite and this is the same as the cable entry grommet.  It is believed that Pellolit was a compound of India rubber and weak mix of the Bakelite compounds giving a flexible (only slightly) but hard to the touch material that could be deformed by mild heating.  Ever noticed how the earpiece covering peels off, sad isn't it.

Question: Do I need a separate Bellset for this phone to work?
Answer: Yes, you must have a Bellset No. 1 or a Bellset No. 25.  These Bellsets include an induction coil which is an essential part in the transmission circuit.  A standard bell will not suffice e.g. Bell No. 1.  Follow this link for a description of the difference between a bell and a Bellset.

Question: Did the GPO Candlestick phones come with any transfers or polished brassware?
Answer: Definitely not.  The GPO always went for easy to maintain equipment and none of their apparatus had superfluous decoration.  The brassware was always painted black.

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Last revised: September 13, 2023