PXML No. 63
APPROVAL No. S/1000/GF/1981/PR

See also Herald A & Herald C

Click here for the full range of Herald/Pentara telephones

Click here for socket wiring

Click here for information on identifying a specific model

Sales Brochure (Pentara 100) - MER193

Sales Brochure (Pentara +Plus) - PHME4180

Herald C Plus is marketed as:-
Merlin S5102 - Herald C Software V8.3 with TX51-54 Terminals.
Pentara 100 - Herald C Software V8.3 with TX54-58 Terminals.
Pentara 100E - Herald C Software V8.4 with TX54-58 Terminals.

Herald C Plus is marketed as:-
Pentara +Plus - Herald C Plus Software V10.0 with TX54-58 Terminals (Ice Grey) and TX65-69 terminals.

The Herald C Plus was marketed as the Pentara +Plus Phone System. A further enhancement of the Herald systems, it incorporates the existing features and facilities of the previous Herald generics, plus some additional ones.

The introduction of version 10.2 (build No 7944) software in February 1992 allowed the use of a Visually Handicapped Operators Console (VHOC). The Console, incorporating a speech synthesis board, is a modified TX68 with a Plantronics headset.

A standby battery shelf was available for new installations and systems upgraded to Pentara +Plus. Typical standby time is between 40 minutes (Single Battery, 3 Shelf System) to about 6 hours (3 Batteries, Single Shelf System). When providing standby power, only Power Units SA20554 may be used in the extension shelves.

Systems can be configured in Herald Assembly Centres using Pentara Documentation System (PDS) or on site using the Self Configure option. Once installed, system and extension facilities can be altered by the customer.

The Pentara Plus Phone System is intended for new customers. Existing Herald A, 100B, B8, S5102, Pentara and Pentara l00E systems can be upgraded to Pentara Plus.

Made by Philips Business Communications Systems

Approved for direct or indirect connection to the PSTN and LD or MF4 signalling by working as a (List B or D) subsidiary system connected to a (List C) system.
Recall can be Earth Loop (300ms) or Timed Break (66ms or 300ms).


Herald Pentara Plus ASU 1A1/SA20579:-
Version 8.A, 8A.AF
Version 10.0B, 10C (IC 10-13 are marked with the software identification)
Version 10.1, 10.2

Call Logging ASU 1A1/SA20572:-
Version 2.5) IC 22 For use only with processors fitted with v8 software
Version 2.7)
Version 2.8)
Version 10.1 (For use only in association with processor 1A1/SA20579 fitted with V10 software)

Speech Synthesis Card SA 20567:-
Version 3.1 IC 3 marked V3.1
Version 1.0 IC 7 marked Vl.0
Version 1.2 IC 7 marked V1.2 - Pentara +Plus
Version 5.1 IC 7 marked V5.0 - VHOC additional board

Music on Hold Card SA 20568:-
Version 3.0 IC 1 marked V3.0
Version 1.0 (The Entertainer) IC 7 marked V1.0
Version 2.0 (Greensleeves) IC 7 marked V2.0

Pentara + Plus
The Product Summary: 17/10/88

Product Summary
Originally launched as the Herald Phone System in April 1981, the present version is known as the Pentara 100E and has been derived through four upgrades and includes many facilities and features not available on the original. The product is being further upgraded with the introduction on the lst. January, 1989 of the latest version, to be called Pentara +Plus. However, any Herald or Pentara Phone System of any of the earlier versions is capable of being upgraded to the latest version and this is perceived to be one of the product's major strengths as it will assist the Business to protect the installed base until a superseding product becomes available.

Pentara has emerged virtually unscathed from the economic depression of the early 1980s and is remarkably resilient. Similarly, there has been no noticeable reaction to political and social/cultural trends.

The Phone System can be used as a Key System using the TX52-58 Series of Feature Phones; it can be used as a PBX; and it can be used as a hybrid system mixing both PBX and Key System working.

It is a modular system - the first shelf can accommodate 9 Slide-in Units and a typical single shelf system would be 6x16. Up to two further shelves may be added. A Battery Shelf is also available for mains failure dropback giving between 2 and 6 hours service depending upon system size and battery capacity.

The capacity of the system is 116 ports including exchange lines, extensions and private circuits, using 20 highways. The nominal maximum size is 16 + 76 although the average size provided is 8 + 24.

Demand is still buoyant and the product is in good standing with customers. The recent introduction of a rental option makes the product even more attractive. Particular strengths axe its versatility, modular growth capability, wide range of features and networking capability.

Network requirements - Exchange line loss must not exceed 10 db minus the loss at 1600Hz of the longest extension. Loop calling Exchange line with loop resistance of 1500 ohms max.

An 'average' system would comprise of the following components. The Central Processor Unit (CPU); 2 x Full Facility Line Cards;  l x limited Facility Line card; 4 x Extension Boards (4-Port 4-wire with Display); l x extension Board (2-wire Telephone 8-Port); and Featurephones as listed in the next paragraph.

Key Customer Benefits and Main Selling Points
Pentara is a popular, fle3n'ble and feature rich system which allows customers to easily make any alterations to the programming themselves without the need to call in an engineer.  Individual buttons can be pre-programmed for fast facility selection and repertory dial numbers; and flexible allocation of exchange lines to extensions allows calls to be presented where required. The system can be tailor-made to a customer's individual requirements, as either a PBX, a Key System, or a mixture of both to provide a hybrid system, and either stand alone, 'piggy-backed' off another system, or networked.

Originally marketed as the "Herald" when launched in 1981, the system is not only the eldest product in the Medium Switch Portfolio but also enjoys a dominant position with some 65% share of the medium-switch sector (nominally 16-80 extensions). Progressive upgrades have enabled its market position to be maintained and also noteworthy is the ability to upgrade early versions to the latest standard.

Concerning Pentara is positioned right across the Medium Switch Portfolio in that because of its hybrid/working capability it can compete with any other product to some degree. Regarding, it is positioned in the 15-50 extension range, centred on 18-30 extensions.

The main perceived shortcoming is that traffic handling capacity does not allow large systems with heavy incoming call rates eg enquiry bureaux. However, the facilities broadly meet the needs of the type of customer within its catchment area.

Competing products
Internal (BT portfolio) - below Pentara, OCTARA - a relatively new Key System, used mainly in stand-alone situations, which is cheaper than Pentara, and can capitalise on its digital capability. Above Pentara, TSX50 - a brand-new PBX using fully digital technology which is marketed as being "for both now and the future', but it competes only partially with Pentara in that it is a true PBX and does not offer the hybrid working of Pentara. Also MONARCH SE120 - limited competition because of price; this system is network oriented.

External competition comes from the following - SDX40 (& SDX40E) from STC; GX1232 from Panasonic; Masterline 1236 from Plessey; London 32 & 64; SX10 (& 10E) and SX20 from Mitel; GEC28 from GEC; Alphalink;
Vision 2000; Telrad 1632; Thorn ACD

Customer profile
There is no sharp customer profile or clearly defined segment/ sector experience has shown the system as having universal appeal through being able to meet the requirements of the market from the small Key System user to a large PBX with a majority of telephones plus a handful of Featurephones; and from a single- site user to a multi-site user with a nation-wide speech network.

Installation summary
The system comprises of a free standing central unit of one or more modules, Pentara Phone System terminals and, where required, loop-disconnect, MF4 or dual signalling (2-wire) telephones with earth recall. The control module(s) are connected to a box connection by cords, 3 metres in length terminated on "226" type connectors. The terminal cords are also plug ended and are inserted into secondary type Line Jacks.

The Pentara Phone System will normally be provided as a self-configured system although a fully customised system based on a customer's individual
needs will also be available. There are two modes for self-configured systems:

PABX MODE - All I/C lines ring the operator and all extensions have 0/G access to all lines.

KEY MODE - All I/C lines ring first 20 extensions and all extensions have 0/G access to all lines.

Once a system has been self-configured it can be customised on site by anyone using dial-up codes at individual terminals. A fully customised system can be produced by obtaining a database using the Pentara Documentation System (PDS). Documentation can be produced for either configuration using PDS.

Pentara terminals are connected to the box connection by 2 pairs of wires (one pair for speech, the other pair for data). The Central Processing Unit (CPU) houses all the equipment for a system, including power supply equipment. It is a standard requirement that the customer makes available a 'clean' electrical supply.

A single mains lead from the CPU is connected to a 13 amp plug (not supplied with the equipment) and protected with a 7 amp fuse. A second 13 amp socket is required for use with test apparatus.

Warranty and maintenance arrangements summary
The Pentara Phone System is covered for one year parts and labour when the system is sold. A maintenance contract must be negotiated at the time of sale and the tariff is based upon the component build-up of the system. Rented systems include the maintenance costs within the rental tariff. British Telecom is the sole approved maintainer.

Launch Timetable lst Jan 1989
Withdrawal of new sales of Pentara 100E.
Introduction of Pentara + Plus using V10.0 software.
Withdrawal from sale of B8 Upgrades.
Introduction of upgrades from Herald A and 100B (B5) to Pentara +Plus Introduction of Pentara Documentation System (PDS) on M5000 Series (IBM compatible) computer

June/July, 1989.
Withdrawal from sale of upgrades to Pentara 100E (V8.4 s/w).
Introduction of upgrades from Herald B8, S5102, Pentara 100 and 100E to Pentara + Plus using V10.1 software.
Introduction of replacement for Herald Documentation System (HDS and H3S) on M5000 (IBM compatible) computer.

The present product, therefore, is to be replaced by Pentara +Plus with effect from lst January, 1989. At the same time the B8 Upgrade will be withdrawn and replaced with a new upgrade. Herald A and Herald 100B (provided not already already upgraded by the use of a B8) will have a change of CPU to upgrade and a new engineering procedure allowing 'suck and blow' data transferral of the existing database on the customer's premises.

During June/July 1989, a revised version of software will allow the 'suck and blow' upgrade procedure to operate to 'C' Processor systems (Herald S5102, Pentara 100 and Pentara 100E) allowing upgrades with just a change of processor, and Herald A and 100B systems already upgraded with the use of a B8 Upgrade, with a change of shelf.

The Pentara is a medium-sized analogue Phone System which can be used as a Key System (incoming calls answered directly by extensions), a PBX (incoming calls intercepted by a dedicated operator), or as a Hybrid (some calls answered by an operator/ receptionist and other calls by extension users, as determined by the user at the time).

The system can: stand alone; be piggy-backed on, or interconnected with, a host system; or form part of a switched speech network.

Extension instruments comprise any mixture of:
a) a specially-featured operator's console;
b) a range of dedicated Featurephones;
c) standard two-wire loop-disconnect and/or MF telephones

New systems are either self-configured on site at installation or pre-programmed in the Data-entry Section associated with Herald Assembly Centres prior to installation to meet customer's precise requirements. All systems can be subsequently reprogrammed either by BT or by the user, depending upon the scale and type of the changes required. It is envisaged that all systems in the generic range will be capable of being upgraded to the current software/facility status.

USP: a universal phone system in that it offers a mix of Key System and PBX working, whether used in a stand-alone mode or as part of a network, plus flexibility and a high degree of customer -programmability.


Title Marketing Name launch Date Approx sales
Herald A Herald (A) Apr 1981 22,000
Herald B (v5) Herald 100B Apr 1983 18,000
Herald C (v8.3) Herald S5102 Sept 1984 2,000
B8 upgrade B8 upgrade Dec 1984 *
New low profile terminals Pentara 100 Apr 1985 *
v8.4 software Pentara 100E Jan 1986 *
v10 software Pentara +Plus Jan 1989
* 14,000 until Jan 1988

There are two versions of Exchange Line Interface Card:-

a) 2-Port full facility which contains 2 exchange line interfaces on the one card which are each capable of generating loop disconnect or MF4 signalling, earth/timed break recall plus power fail switching of both circuits, meter pulse detection and external Music-on-Hold (if provided as an optional extra). Ringing/loop and dial tone detection are performed by the card.

b) 4-Port limited facility containing four exchange line interfaces on the one card each capable of generating loop disconnect or MF4 signalling, and earth/timed break recall. Ringing/loop and dial tone detection are performed by the card. It should be noted that there is no provision on this card for Music- on-Hold to external callers. NO POWER FAIL CIRCUITRY IS PROVIDED ON THIS CARD.

There are two versions of Extension Interface Cards:-

a) 4-Port 4-wire Display Terminal Interface Card which is designed to support 4-wire dedicated terminals. Speech transmission circuits similar to the 2-wire interface card are used but a control IC for the interchange of data between the control card and the terminal, and data transmit/receive and power feed circuits are incorporated. The card is able to support terminals fitted with message displays and 2-wire telephones. Four circuits are provided per card.

b) 2-wire Telephone Interface Card provides eight circuits per card and will accommodate loop disconnect signalling, and MF4 if an MF4 options card is available.

NOTE Both extension interface cards require MF4 Option Cards when used with MF4 2-wire telephones.

The Optional Extras
DC5/10 This interface card provides two circuits which are each able to make outgoing calls and receive incoming calls over SSDC tie lines. Signalling, either SSDC5 or SSDC10, is dependent upon which system has been link selected for each circuit on the card. The SSDC5 system employs four wires, two for speech and two for signalling. The SSDC10 system employs two wires carrying both speech and signalling.

SSAC15 is a tone type in-band signalling system for the link-by-link
transmission of supervising signals and 1Opps digits. It uses a single frequency 2280Hz tone in each direction on a 4-wire transmission path. The absence or presence of this tone indicates a specific signal dependent on its position in the signalling sequence and in certain cases, on its duration. When the circuit is idle a continuous low-level signalling tone is present in both directions. SSDC15A can be described as a Tone On Idle signalling system. Each SSAC15 interface provides one SSAC15A circuit.

When Pentara 100 was launched the terminal range changed to the current 'Low Profile' range . The colour range offered was originally Brown and Stone, but Brown was dropped during 1987. To coincide with the launch of Pentara +Plus a new colour, Ice Grey (as Viscount specification) is to be introduced and the Stone variant is to be withdrawn as stock reduces to nil. The colour change applies to all terminals (TX54, 55, 56, 57 and 58) with the sole exception of the TX52PF which will continue to be available in both Brown and Stone until existing stocks exhaust (this is not expected to be earlier that January 1990 at current usage rate). It should be noted that the TX52PF is withdrawn it will not be replaced.

A Telephone terminal can also be provided using any of the current range of telephone instruments. However when MF4 signalling is provided to the network and TouchTone instruments axe required, reference should be made to the Customer Field Note - VOICE GENERAL No. 009, "TOUCHTONE/MF4 SIGNALLING' to ensure that the correct version of telephone is provided.

(TouchTone is a trade mark of British Telecom in the United Kingdom.)

Customisation using PDS
The interactive program used to configure the customer discs and load and recover the database from the system is called the Pentara Documentation System (PDS). This IBM compatible software designed to run on the M5000 Series PCs, will eventually replace the earlier software run on the Rair Black Box PC and which was known as Herald Documentation System (HDS & H3S).

PDS offer certain options which are not available from self-configuration, ie:-

Prime Line Answering
Repertory Dial Block
Internal Digit Barring
Call Barring
Call Logging
Route Barring
Manual Private Circuit working Altering the Number Scheme

Details concerning the interactive program for configuring a Pentara system together with a more detailed description of PDS options are contained in the Data Entry Guide (TPU 1042).

New features and facilities will continue to be developed for the system and the software will be updated to new versions and introduced from time to time. For quick reference the above table lists the various features and facilities available in the various releases of software. Reference should be made to the appropriate User and System Programming guides for further information on operating procedures and service codes.

The Upgrade as a Product
The availability of a new upgrade to Pentara +Plus enables BT to standardise the end result and make things simpler in the field as a result. The standard upgrade to Pentara +Plus will, therefore, include Version 10 software and the Modem card as well as Speech Synthesis.

Pentara +Plus introduces a major new engineering facility, colloquially known as 'suck and blow' which is not advertised in the facility list. It simplifies the upgrade process, but is itself an extremely complex suite of software programs. Hence it has been necessary to split its introduction into two issues of software. Version 10.0 will only support 'suck and blow' from Herald 'A' and 100B (B5) systems to Pentara + Plus. Version 10.1 will support additionally Herald B8, S5102, Pentara 100 and Pentara 100E (the full range). Please refer to the launch timetable in paragraph 1.2 for availability of version 10.1.

In the marketing of upgrades account has to be taken of the various differences between versions of Herald and Pentara's, for example Herald 'A' had no Call Logging capability; Herald 100B included Call Logging within the processor card; and Herald /Pentara ('C') systems (Herald S5102, Pentara 100 & 10OE) offered Call Logging as an optional (and chargeable) extra.

When the B8 Upgrade was launched, the basic package comprised the B8 processor, a Call Logging Card, and a Speech Synthesis Card though in practice many Districts only provided a Call Logging Card with the Upgrade if the customer was already using Call Logging. In conjunction with the Upgrade, if the customer ordered additional extras such as Music-on-Hold or Powerfail Terminals there was a requirement to change out Limited Facility Line Cards for Full Facility Line Cards, and the customer was offered the facility of changing their cards out at a special rate of £75 per two lines (or part).

The upgrade to Pentara +Plus is two separate products - a new Upgrade shelf (in effect the new Kit 1 A/P) which will be used to upgrade all Herald A and 100B versions and which will be known as A/B/B8 Pentara + Plus Upgrade; and a Processor change to upgrade all 'C' processor systems (Herald S5102, Pentara 100 and Pentara 10OE) which will be known as S5102/Pentara to +Plus Upgrade.

A/B/B8 Pentara + Plus Upgrade is so called because it is used to upgrade to Pentara +Plus status Herald 'A' and 100B systems (including Herald ('A') and 100B systems which have already been upgraded by B8). It consists of a basic Pentara +Plus CPU + Speech Synthesis + Modem Card + Options Motherboard. The installation of the upgrade is achieved with an installation engineer taking out to the customer's premises the above components. The CPU is connected to the existing CPU (and to power) and two pegs operated which then bring into operation a 'suck and blow' process where the database programme written into the existing system is 'blown' into the new CPU during which process the existing system continues to operate as usual. Upon completion of this process, the existing CPU is replaced with the new CPU and the customer's existing cards housed in the existing shelf changed over into the new CPU, and the upgrade is complete. The customer can now invoke the new facilities and undertake any reprogramming they wish.

Should the customer require any additional optional extras, this work can be carried out at the same time and on site unless the customer requires any of those facilities only programmable in the workshop (listed in 1.3.6). The normal standard tariffs will apply. If the upgrade includes a requirement to change out Limited Facility Line Cards for Full Facility Line Cards the same considerations as those given in the B8 upgrade package apply with the exception that the charge is now £100 per two lines (or part). If the customer is already using Call Logging (either via the system on 100B (B5) or a card on B8) it will, of course, be provided on change-over either by providing a Card on the former or by changing over the existing card with the other cards. If the customer requires Call Logging or Display (on TX54 and/or TX58 terminals) for the first time, at the same time or at any time after the upgrade, the card (and V24 Port) should be provided and charged for at the price listed in the Pricing Manual. (The price for the Call Logging Card includes provision of the V24 port.)

S5102/Pentara to +Plus Upgrade is so called because it is used to upgrade to Pentara + Plus status Herald S5102 and Pentara 100 & 100E systems. The installation is similar as that described above under A/B/B8 Pentara +Plus Upgrade Kit above except that instead of a new CPU the installation engineer uses a recovered 'C' type CPU with a new Pentara + Plus Processor and after the initial 'suck and blow' process only the processor is changed. The customer can now invoke the new facilities and undertake any reprogramming they wish.

Should the customer require any additional optional extras, this work can be carried out at the same time and on site unless the customer requires any of those facilities only programmable in the workshop. The normal standard tariffs will apply. If the customer is already using a Call Logging Card this will, of course, remain in the system. If the customer requires a Call Logging card for Real time Display (on TX54 and/or TX58 terminals) at the same time or at any time after the upgrade, the card (including V24 Port) should be provided and charged for at the price listed in the Pricing Manual.

Although the upgrades are two distinct products, until version 10.1 software is launched it becomes necessary to consider which of the installed base can be upgraded using the 'suck and blow' procedure introduced with Pentara +Plus and which systems will only use this method with the introduction of version 10. 1 software. Standard upgrades to Pentara + Plus can, therefore, be arranged into 3 distinct groups:-

Herald 'A' and 100B (B5) (not upgraded by B8) to Pentara + Plus
Hardware - Pentara +Plus CPU
Speech Synthesis Card
Modem Card
Options Motherboard
Call Logging Card (only on 100B (B5) systems where the customer is already using call logging.
Box Conn 337A

Software V10.0 or V10.1
Herald 'A' and 100B (B5) with B8 Upgrades, to Pentara + Plus
Hardware - Pentara +Plus CPU
Speech Synthesis Card (if not already fitted)
Modem Card
Options Motherboard
Box Conn 337A

Software V10.1
Herald S5102 and Pentara 100/100E to Pentara +Plus
Hardware - Pentara +Plus 256k Processor
Speech Synthesis Card (if not already fitted)
Modem Card
Options Motherboard (if required)

Software V10.1
Standard upgrades include the equipment listed above within the tariff. There is no reduction in the price should the customer already be using some of the equipment e.g. Modem Card. It also includes the transfer on site of the existing database into Pentara +Plus using the 'suck and blow' method. PDS work is not included in the standard tariff.

Should the customer require any additional optional extras, this work can be carried out at the same time and on site unless the customer requires any of those facilities only programmable in the workshop. The normal standard tariffs will apply. If the upgrade includes a requirement to change out Limited Facility Line Cards for Full Facility Line Cards the same considerations as those given in the B8 upgrade package apply with the exception that the charge is now £100 per two lines (or part).

Although version 10.1 software will not be available at the same time as the launch of Pentara +Plus, it will possible to upgrade Herald B8, S5102 and Pentara 100/100E systems to Pentara +Plus. However it will be necessary to configure the database from scratch; it is not possible to recover the existing database by the use of PDS 'suck and blow'. A system upgraded in this way should be charged standard tariff if self-configured, or standard tariff plus the PDS charge if the PDS workshop is used.

Market Analysis
Such is the versatility of Pentara that it appeals to a very wide spectrum of the market. Although having a maximum capacity of about 16 + 68 (subject to some flexibility depending upon configurations the average size is considered as 8 + 24). A notable point is that this average has been constant throughout the 7-year life of the product, despite the significant improvements in features and facilities arising from a series of software and hardware upgrades.

The system may be regarded as being sold exclusively into the Business segment of the market, and within this the key sectors are single-site installations, multi-site installations and networks. As with most products, the volume distribution of sales matches the density of businesses and no oddities in geographical distribution have been perceived or are expected.

Demand for Pentara has been remarkably buoyant throughout its life and has not been affected by economic factors such as the depression of the early 1980s. However, annual sales peaked in 198213; since then volumes have fallen year by year and this trend is expected to continue until the end of the product's marketing life.

Total sales since introduction in 1981 are some 57,000 and the installed base at 31 December 1987 was 48,000. The sales out-turn in 1987/88 was 3786 systems, and the January 1988 QRF/MTF Review volumes for Year 1 onward are :



















* To be achieved during the first half of the financial year, after which a superseding product is expected to become available

There is also a lucrative market arising from milking the installed base through the sale of additional and/or replacement features, facilities and terminals, and from upgrading older systems of earlier versions to the current status. A further 4500 systems could be sold before the product is withdrawn, leaving an estimated residual installed base of 52,000 systems, and although there is an existing unwritten commitment on BT to provide maintenance support for 7 years after a product is withdrawn from the portfolio, it will also make sense for BT to sell into the declining base only for as long as it remains economically practicable.

Stock Planning, Ordering and Delivery
Pentara items on COPS we indicated in subsection 3.3. Current COPS ordering procedure as detailed in the current District COPS User Manual should be followed.

All Control Units, Extension Units, and Standby Battery Units have the following overall dimensions:

- Width: 520mm (20.5 in)
- Height: 218mm ( 8.6 in)
- Depth: 408mm (16.1 in)





























Depth includes handset

Standby Battery Unit:
(with Alarm Card) 7.92kg 17.461b
50v Standby Battery 10kg 221b
TX57 Terminal 1.038kg 2.291b
TX58 Terminal 1.088kg 2.41b
TX55 Terminal 0.830kg 1.831b
TX56 Terminal 0.842kg 1.861b
TX54 Operator Terminal 1.476kg 3.251b
TX52PF Powerfail Terminal 2.00 kg 0.911b

Connection Box:
1-Shelf System 1.962kg 4.331b
2-Shelf System 4.084kg 9.001b
3-Shelf System 7.194kg 15.861b

Taken from Pentara +Plus manual 1988

Test Items                                            Item Code
Testers 364A (formerly Herald Audio Tester)           314566
Card Test 4B (Highway Tester)                         314700
Test Access Unit 8A.  (Now obsolescent superseded by)  314300
Modem Card  SA 20569                     or           374724
Datelphone 4122                          or           251493
Datel Modem 4124X in                                  251583
Datel Unicase 4001hx                                  251630
BACK Home page BT/GPO Telephones Search the Site Glossary of Telecom Terminology Quick Find All Telephone Systems

Last revised: May 05, 2023