For many years the British Post Office had a monopoly of supply of most items of subscriber apparatus (customer premises equipment or CPE) used on the public network in Britain. Where it did not have this monopoly, such as on PABX equipment of over 100 extensions capacity and telephone answering & recording machines (TARMs), it stipulated that customers had to buy them (as in the case of PABXs) or rent them (as for TARMs) from a restricted number of approved suppliers. On purely private systems (PAXs for instance), these rules do not apply, although where PAX systems were interconnected by private circuits rented from the Post Office, the apparatus still had to meet BPO standards.

All this came to an end around the same time as the general deregulation of telecommunications in Britain. Following the decision to liberalise the supply of CPE, the Department of Industry Consultative Committee on Telecommunications issued an announcement in 1981. This  recommended the phasing in of new equipment over a period of about three years, in order to create an 'orderly  transition'  into the competitive environment, where new suppliers as well as BT itself would  have an opportunity of researching new products as well as improving the old ones over this transitional period.

The phasing was expected to follow this pattern:

 Phase 1, First Year (1981)

  • Internal wiring
  • Jack plugs (and hence sockets)
  • Telephone handsets, based on BT ‘Special Range’ specifications, and
    intelligent telephones
  • Explosive atmosphere telephones
  • Telephone answering machines
  • Modems and, where appropriate, multiplexers
  • Callmakers (i.e. repertory diallers)
  • Flexibility switches and patching frames
  • Network management systems
Phase 2, Second Year (1982)
  • Lift telephones
  • Weatherproof telephones
  • Multiterminal telephones
  • Trunk barring devices
  • Bells
  • Diversion switches
  • Flexibility, fallback devices
  • Teleprinters
  • Radiophones
  • Radiopaging receivers
  • House exchange systems (key systems)
  • Key and lamp units
  • Call diversion equipments
  • Alarms using the PSTN
  • Specialist telephones (e.g. for the handicapped)
  • Loudspeaking telephones
Phase 3, During Third Year (1983)
  • Conference telephones
  • Cordless telephones
  • Private payphones
  • Private meters
  • Private branch exchanges (including ancillary equipment such as automatic call distributors, or other items where they arise)
  • Private Telex branch exchanges 
  • Facsimile machines
  • Other interconnect equipment (e.g. control and processing equipment for radiophone services)
  • Error detection units
  • Autosender
  • Broadcast units

Answering machines

Answer-only machines, as opposed to telephone answering & recording machines (TARMs), were supplied by the Post Office. In 1980 there were three models:

  • No 1.  Answers incoming calls with a 20-second announcement, repeated once.
  • No 2.  Answers incoming calls with an announcement of up to two minutes,
    depending on your requirements.
  • No 3. Answers incoming calls with an announcement which can be 30 seconds, or two or three minutes. You record on to cartridges, so you can, at modest cost, build up a library of announcements suitable for any situation.
    All three are attractively styled, desk-top models. Connection and rental charges aren’t exorbitant. Send the Freepost card for more information, or give us a number to call (don’t worry — we’ll keep trying until we get in touch).


In September 1979 the Post Office announced a change in arrangements for the private supply of telephone answering machines. From April 1980 customers will be able to buy as well as rent machines from ‘Approved’ suppliers. 

Customers will still need to make individual application to the Post Office to use machines in connection with the public telephone system. We shall normally be happy to allow this if the machine is of a type which has been certified by us as meeting our standards of safety and compatibility. Machines must be obtained from suppliers who have entered into an agreement with us undertaking to comply with our requirements concerning the supply of these machines.
Currently [1980] over 70 types of acceptable answering machines are available from the following approved suppliers:

  • Agovox
  • Ansafone
  • Ansamatic
  • Europhone
  • Mailing & Mechanisation
  • Recordacall
  • Robophone
  • Sentriphone 24
  • Shipton Communication
  • South Eastern Electronics
  • Storacall
  • Teletronics
  • Valemead Finance
  • Zettler
A number of other suppliers intend to enter the market with suitable machines, and we ourselves are in the course of adding answering and recording machines to our wide range of products (we already have 3 models of answering-only machines available).
_ We strongly recommend customers, in their interests, to check that any machine which they wish to buy or rent is of a type warranted by the supplier to have been certified by  the Post Office as described above. Absence of certification means that use of a machine in connection with the public telephone system has not been authorised by us, and we will require that such a machine be disconnected from our lines.
[At this time a spirited supplier of non-approved models of TARM was Mr Ron Collins, who ran a business called Callsaver (originally in Goodge Street, later Caledonian Road, London). His machines, imported from the USA and converted to work in the UK, cost a fraction of the approved models. Another 'problem' was the importing direct from the USA of models that looked the same as those approved for use in the UK but which met FCC rather than BT standards. Technically some of these were very different from the UK model; some drew much more line current and under fault conditions the line transformers could saturate, overheat and catch fire (actual case study). Others failed to drop the line satisfactorily at the end of calls; one importer tried to sue BT for lost income until it was pointed out that the true reason for his missed recordings was a defective, unapproved answering machine!]

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