Formed in 1870 as C Telegraph Troop, Royal Engineers, the Army’s signalling service expanded rapidly during the 2nd Boer War and the First World War. Growing from a small telegraph unit into the RE Signal Service, and in 1920, a Royal Warrant established the Corps of Signals, which King George V soon granted the title Royal Corps of Signals [33][31].
Other commonwealth Corps of Signal are (in bracket date of first signal unit preceding the Corps formation) [33]:
This essay presents the timeline from the first to the last portable analog wireline local battery field telephones used by the British army and other commonwealth armies. Information is based on original documents from the time, all sources are listed at the end. Images are sourced from the referenced publications, while unreferenced color images are from instruments in my personal collection.
The British army started using telephones during the 2nd Boer War 1899 to 1902. Apart from using civil material first army specific portable models were introduced there based on Ericsson products [3] [33]. The C. Mk. I. a Magneto/Bell device corresponding to the Ericsson No. 390, and the D. Mk. I., a lightweight buzzer only device, based on the description in "Instruction in Army Telegraphy and Telephony, 1914" it was most probably an Ericsson No. 394 [1][3][6]. The D. Mk. II. was a improved design of the D. Mk. I [2][3].
"Instruction in Army Telegraphy and Telephony, 1914" also mentions a heavy Telephone Set A. (18kg) and a Telephone Set B, set B is not described further only in the summary list, based on same weight and battery usage mentioned in list it is assumed the set B. was a slightly older similar set than C. Mk. I. Sets A, C. Mk. I., D. Mk. I. and D. Mk. II. are marked as obsolescent and B as obsolete by 1914 [3].
Telephone set. Portable, A: [3]
This instrument was designed as a portable set for Telephone set, coast communication work;
it is contained in a 1'3" x 10" x 1'1" case, and weighs 40 lbs., so that its portability is somewhat questionable.
Telephone, hand. A, is included in the set, and two Cells, electric, dry A are used with it, space for them being provided in the case, but must be demanded separately.
The set includes a plug and double flexible cord 6 feet long connected to the line terminals, which is carried on a small drum on the side of the case. The case is fitted with a shelf for writing a message.
Telephone set. Portable, C. Mark I: [3]
This is a portable instrument, designed by Messrs. Ericsson, and was bought in large quantities for use in South Africa.
It is very handy and portable, but not suitable for use in rain, nor are the parts easy of access for the lineman.
Its weight is about 18 lbs.
The set includes hand telephone C, Mk. I, and two P size dry cells are used with it, space for them being provided in the box.
C. Mk. I. [6]:
Internal Connections, D Mk. I.: [2]
Telephone set portable D Mk. I consists of a complete telephone with vibrator call, and space for a battery. It is contained in a leather case, and weighs 4 lb. 6 ounces. The complete instrument consists of the following parts:
Ericsson 394 [1]:
Internal Connections, D Mk. II.: [2]
Telephone Sets Portable D (Mark II), Diagram Showing Connections [4]:
When the First World War broke out in 1914, the Royal Engineers Signal Service numbered fewer than 6,000 men. By the end of the conflict, their ranks had grown to nearly 70,000 signallers. Early communications relied heavily on traditional methods such as optical signalling with flags and lamps, and runners, dogs, and carrier pigeons—over 20,000 pigeons were in service by the war’s end. For trench communications, single-line earth-return circuits were first employed, though they proved vulnerable to enemy interception. These were later replaced with two-wire systems, and ultimately with the Fullerphone, which made interception far more difficult [33][31].
On the equipment side, improvements had begun just before the war with the introduction of the C.Mk.II and the D.Mk.III. telephones. To meet the enormous wartime demand, additional designs from Stevens (made by International Electric Company Ltd. Kilburn) and Siemens Brothers were adopted [5] [6], along with linesmen devices from the General Post Office [3][33][43].
Field Telephones. Introductory. [4]
It is a matter of common knowledge that the object of any telephone is to enable two people to talk to one another at a distance which is outside the range of their voices.
This is done by converting the vibrations or disturbances in the air caused by speech into corresponding electrical vibrations or "current", which are carried from one station along some "conducting" material to the far station (where they are converted to air vibrations) and back to the sending station.
The original speech is thereby reproduced at the far station.
Telephone set. Portable, C. Mark II: [3]
This instrument has been specially designed to obviate the difficulties experienced with Mark I.
The case has a lid at each end : one, fixed with a simple hook, gives access to the hand telephone, generator handle, and is for the use of the operator;
the other, fixed with screws, gives the lineman a convenient means of testing the internal arrangements.
The weight is about 20 lbs., and the box is fairly waterproof whether open or shut.
Its dimensions are 11 inches high by 10 inches deep by 5 inches wide.
Hand telephone C, Mark II, and C telephone ear cushion forms part of the set, and two "Cells, electric, dry P" are used with it.
C. Mk. II.:
Telephone set. Portable, D. Mark III: [3]
This instrument has superseded the Mark II.
The important improvements in the Mark III. are:
The brass base of the ebonite case is connected to the earth terminal, which enables the instrument to make earth when placed on the ground without an earth pin.
The whole is contained in a leather case of two compartments, one taking the telephone hand and head receiver, the other the instrument.
D. Mk. III. [5]:
Telephone Set Portable D (Mark III), Diagram Showing Outside Connections [4]:
Siemens' Field Telephone: [5]
This instrument [...] resembles the D Mark III in the respect that a polarised buzzer is used.
A separate induction coil is employed, however; and a single receiver is provided, forming part of a hand combination.
Two dry cells are used; and the various parts and terminals are fastened to a wooden frame, which, together with the hand combination, fits into a leather case provided with a sling.
This case has a metal base, connected to the earth terminal, so that when placed on the ground and coupled to line, the telephone is ready for work.
For all practical purposes it may be regarded as equivalent to the Mark III [...].
Stevens' Field Telephone: [5]
Amongst the telephones used to augment the Service pattern, the form devised by Stevens (Patent 23172, 1911) has been much used.
[...]
A simple buzzer, operated by the primary of the induction coil, is used, and & second adjusting screw, external to the circuit, is provided for the purpose of regulating the throw of the armature and producing a keener note.
Four dry cells are provided, only two of which are normally used; but when the note of the buzzer weakens, the other two may be brought into the circuit by turning a knob.
[...]
he receiver and microphone are separate, each being of watch form, and strongly constructed.
The outfit is packed in a leather case with sling, the total weight being 6 ½ lb.
Siemens' and Stevens' Field Telephone [5]:
The Royal Corps of Signals was established in 1920, tasked with providing the British Army’s vital communications. During the inter-war years, advances in wireless technology were made, yet at the outbreak of the Second World War the majority of communication still relied heavily on traditional line systems. In 1939, the Corps numbered some 36,000 men. Over the course of the conflict, the scale of operations grew dramatically, and by 1945 its strength had expanded to around 150,000 personnel.
At the beginning of the conflict, the sets F.Mk.I and D.Mk.V were introduced. As the war progressed, these were followed by the F.Mk.II, the L set, and the J set. The D. set was buzzer only and the previous D. sets (but included a polarized ringer to receive magneto calls). The F. sets where a new concept supporting buzzer and magneto signalling (the buzzer still modular could also be replaced with a simple induction coil) and also CB lines. The F. Mk. II. was a modernised/improved version over the Mk. I, using a bakelite instead of a metal case. The L and J sets are lighter, smaller and getting rid of the buzzer option.
Telephone Sets, F, Mark I: [12]
The Telephone Set, F, Mk. I, is a portable instrument for army communication.
It is not normally used forward of divisional headquarters.
It provides the following facilities:
F.Mk.I. [12]:
Telephone Sets, D, Mark V: [11]
The Telephone Set, D , Mk. V, is a portable instrument for field use in Army formations forward of Divisional Headquarters.
It provides the following facilities:
D.Mk.V. [11]:
Telephone Sets, F, Mark II: [21]
The Telephone Set "F" Mk. I* is similar to the Telephone Set "F" Mk. I except for small constructional differences.
The Telephoue Set "F" Mk. II has several changes-namely:
•(b) Induction coils No. 21 replacing Buzzer T Mk. I
although buzzer switch is, still wired up.
(c) Generator, type C instead of Generator, type B.
Telephone Sets, L: [14]
The Telephone Set, L is a portable instrument for army communication.
It is not normally used forward of divisional headquarters, expect by linemen.
It replaces the lineman's telephone No. 44 (G.P.O. type) and may be used instead of the Telephone Set F, to which it is superior both mechanically and electrically.
It provides the following facilities:
L. [14]:
Telephone Sets, J: [19]
The Telephone Set J is a lightweight, portable, immersion-proof instrument for field use. It may be used in any climate.
Facilities:
J. [19]:
A D.Mk.V. (PT&EW, 1940), F.Mk.II. (TMC 1940), F.Mk.I. (Plessey, 1939), and a J. and L. set:
After 1945, the Royal Corps of Signals shifted from wartime demobilisation to Cold War responsibilities. Until the end of the Cold War, the main body of the Corps was deployed with the British Army of the Rhine (BAOR) in Germany, providing the British Forces' contribution to NATO. Signallers also served in overseas operations from decolonisation conflicts to the Korean War. During this period analog wired communication lost importance and was replaced by digital communication over microwave trunk links.
In 1967 "BRUIN", a trunk communication system using encrypted radio trunks, PCM channels and automatic digital exchanges built around of the shelf equipment was introduced and in use until it was replaced in 1984 by "Ptarmigan", a computer—based, automatically switched, mobile and secure military communication system providing voice, telegraph, data and facsimile modes of operation over a wide geographic area. "BRUIN" used standard GPO 706 desk sets, "Ptarmigan" introduced special digital static and mobile subscriber sets. "Ptarmigan" was early retired in 2009 and replaced by the IP based "Falcon" system [45][46][47][48][49].
The F. series instruments were probably in use up into the seventies. In the 70ies the first electronic field telephone PTC 404 (LB, CB) was introduced followed by the last analog field telephone PTC 414 (LB, CB/Aut.) introduced in the 90ies.
Field Telephone, UK/PTC/404: [23]
[...]
Operating the equipment:
Connect the telephone lines to the terminals Ll and L2.
The lines will be connected at their remote end to either a similar magneto telephone or to a central battery exchange as required.
The operating procedure for both modes is as follows [...]:
To call a Central Battery Exchange: Set switch S2 to CBX.
Hold the handset pressel switch depressed to speak or listen.
At the conclusion of the call, release the handset pressel switch and set switch to MAG.
[...]
To call Magneto Systems: Set switch S2 to RING and hold (against the spring).
Depress the handset pressel switch and listen for the signalling tone.
When the tone ceases allow switch S2 to return to MAG.
If necessary, repeat the calling tone by again selecting RING and then releasing to MAG.
Hold the handset pressel switch depressed to speak or listen.
At the conclusion of the call, ring down by selecting RING then MAG with switch S2.
[...]
It may be found convenient to use the equipment in its satchel.
[...]
Note: The handset should be packed with the mouthpiece at the bottom of the satchel.
This enables the audio alarm, which is emitted from the mouthpiece, to be heard via the air holes in the bottom of the satchel.
[...]
PTC 404 [23]:
Combat Field Telephone UK/PTC/414: [24]
The Combat Field Telephone UK/PTC/414 is a 2-wire telephone set designed for connection into 2-wire magneto field telephone systems, or Central Battery (CB) signalling exchanges.
The unit provides facilities for magneto ringing and 2-way duplex speech communication.
Operation is from internal batteries in LB mode, and line powered in CB mode.
PTC 414 [24]:
A PTC 404 and a PTC 414:
Below table gives an overview of above described army issue instruments. The "generation" is my classification. The "Year" is estimated based on earliest mentions in manuals and other publications. All the instruments are also listed on the Global Field Telephones Comparison List.
| Generation | Name | Year | Weight [kg] (incl. Bat.) | Battery | [B]uzzer or/and [M]agneto call | Mentioned in regulations/manuals |
|---|---|---|---|---|---|---|
| 0 | Telephone set, A. | 1899 | 18.2 | 2x Cells, Dry, A. | M | [3] |
| Telephone set, B. | 1899 | 8.2 | 2x Cells, Dry, P. | M | [3] | |
| Telephone set, C. Mk. I. | 1899 | 8.2 | 2x Cells, Dry, P. | M | [3] | |
| Telephone set, D. Mk. I. | 1899 | 2.3 | Special | B | [2][3] | |
| Telephone set, D. Mk. II. | 1907 | 2.5 | 2x Cells, Dry, S. | B | [2][3][4] | |
| 1 | Telephone set, C. Mk. II. | 1914 | 9 | 2x Cells, Dry, P. | M | [3] |
| Telephone set, D. Mk. III. | 1914 | 3.8 | 2x Cells, Dry, S. | B | [3][4][8] | |
| 2 | Telephone set, F. Mk. I. | 1936 | 7.8 | 2x Cells, Dry, S. | B/M | [12][17][21] |
| Telephone set, D. Mk. V. | 1939 | 4.4 | 2x Cells, Dry, S. | B | [11] | |
| Telephone set, F. Mk. II. | 1940 | 5 | 2x Cells, Dry, S. | B/M | [17][21] | |
| Telephone set, L. | 1941 | 4.5 | 2x Cells, Dry, S. | M | [14] | |
| Telephone set, J. | 1945 | 4.1 | 2x Cells, Dry, S. | M | [19] | |
| 3 | PTC 404 | 1975 | 2.8 | 4x 1,5V D | M | [23] |
| PTC 414 | 1994 | 1.8 | 4x 1,5V C | M | [24] |
I could not find documented production numbers for any models. The first with high production numbers must be the D.Mk.III. and based on current availability the WWII era models D.Mk.V, F.Mk.II and J. and L. for sure were made in very significant numbers.
The letter designations seem to have been assigned with the next letter in the alphabet for a new type and generation of devices. The early instruments A. and B. have had assigned their letters most probably after the fact. C.Mk.II and D.Mk.III. seem to have been the first having already had assigned the model designation at develompment/production.
C. was used for magneto signalling and D. for buzzer. F. then was used for a new form of telephone supporting magneto, buzzer and also CB. H. was used for sound powered devices. J. and L. were then just used in sequence for the devices following the F. types. E., G., I. and K. seem not to have been used for any devices.
Gen. 3 analog field telephones were designated PTC (Portable Telephony Communications).
From set D.Mk.III. onwards polarised buzzers with combined function as speech coil were used, standardised for use in the models D.Mk.V and F.Mk.I. and II. as Buzzer T.Mk.I. (T. for telephony, the Fullerphone buzzers used the abbreviation Buzzer F. for Fuller). Early field phones were either built for buzzer or for magneto/ringer signalling (D.Mk.I-III were buzzer devices, C.Mk.I-II. were magneto devices), then for some time the sets were supporting both (F.Mk.I-II., D.Mk.V. had a buzzer and a ringer, but no magneto though). Later only magneto signalling was supported (L., J., PTC), and for the F. devices a replacement coil was available to remove the buzzer function.
A dismantled Buzzer T.Mk.I. [12]:
Spelling Tables were used in the British army, and from at least 1928 onwards also added to instruments [9].
Initially only for a subset of letters a spelling word was used [2][4]:
The letters T, A, B, M, S , P, and V will be called toc, ack, beer, emma, esses, pip, and vic respectively, so as to phonetically distinguish them from similarly sounding letters , and to ensure uniformity no other names will be given them or to any of the other letters of the alphabet.
Later respective words were defined for the complete alphabet [9][10]. A good overview of different British spelling alphabets is given at royalsignals.org.uk [44].
The most used 1,5V element was the element of size S used from the D.Mk.II onwards up to the L. instruments. Initially the S type was a dry element, later S was used for the same size but inert, and X was used for the dry version [10]. This battery type was even NATO standardised as Battery Dry No. 12 NATO Stock N. 6135-99-910-1135, type designation NBA 300 [22].
Elemnts Dry X (MkII 1955, No. 12 1979, MkII replica):
Early sets used different types of then current dry element types. Tele set A used an element dry "A", a cylindrical element of 7 3/8 inches high and a diameter of 3 3/8 inches. Tele set B and C.Mk.I-II used an element dry "P" of similar dimensions than the Ericsson element No. 600 and german type "Feldelement". D.Mk.I. used a special 3V battery from Ericsson, No 602 [1][3].
Finally the PTC instruments used standard D (US/NATO BA-30) or C (US/NATO BA-42) cells [22].
British sound powered sets are the H.Mk.II. which is using the F. design and the H.Mk.III. which is based on the L. set design.
H.Mk.III.:
Tele Set F. High Power No. 1, Mk II: [16]
The Telephone Set F High Power is a portable instrument for army communication on ranges greater than those obtainable with Telephone Sets F.
[...]
The set comprises a modified Telephone Set F, and a valve amplifier.
[...]
The amplifier incorporated in the set is unidirectional, the direction of amplification being controlled by the pressel switch on the handset which must be depressed while sending speech or buzzer signal and released while receiving, if the amplifier is switched on.
[...]
Tele Set F. High Power No. 1, Mk. II. with Battery Box [20]:
Especially in the WWI era GPO linemen devices were also used from the signal corps. The Royal Signal Corps had already historically always a close relationship to the GPO and later BT [33].
Early linemen sets of the WWI era were the 92, 100, 104, 108, 110, and 44 models. Later sets are the 250 (introduced in the 1930ies), the 704 which was also released as military version PTC 405, and the 286 [33][44].
A GPO 110B, GPO 44B, GPO 250 and GPO 704 set:
Fullerphones are British DC telegraphy instruments named after it's inventor A.C. Fuller. Traditional telegraphy, buzzer telegraphy and voice communication were suspect to interception, especially during WWI trench warfare where lines of the different belligerents were constructed very near to each other. The Fullerphone solved this by using very faint DC currents (<2.5uA) with flattened signal edges to prevent any overhear-able induction. To make the signals readable by the operator these faint DC currents were converted into audible buzzing signals (~550Hz) by use of an adapted buzzer gadget. Fullerphones were still used into WWII.
Wireless for the warrior provides excellent technical and historical information about British Fullerphones and similar devices from other countries.
A Fullerphpone Mk. IV. (1939) and Mk. III. (1924):
For office type use the "Instruction in Army Telegraphy and Telephony" from 1914 [3] mentions desk and wall sets which seem to be commercial use models. Later standard GPO sets like the GPO 162, 232 or 332 were used and also modified as scrambler phones [50]. The 60ies/70ies "BRUIN" network used standard GPO 706 sets as subscriber devices [45].
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