PXML No. 85 and BABT/PXML/PBX. 0055
APPROVAL No. S/1000/GF/1981/PR

Click here for Information on the Monarch 120A

Monarch 120A Monarch 120B Compact

Monarch is a range of digital PABX systems. The 120A, 120B, 250C1/2, SE250 and CD250 equipment is housed in single floor standing cabinets. The Compact, SE120 and CD120 consist of table top single or double shelf units while the SE220, SE440 and CD440 are dual cabinet upright systems. The CD220 is available only as an upgrade to an existing 120A/B. The IT440 and CD440 (DP) consist of three or four upright cabinets depending on whether the data option is fitted. DP stands for Dual Processor and this description is being used to distinguish the single processor CD440 from the dual processor model, previously sold as IT440.
Note that the CD440(DP) will not be available initially; the Monarch dual processor model will continue to be sold as IT440, with version 16 software. The launch of CD440(DP) will be announced in a Marketing and Sales Circular. In addition to IT440, only CD systems and upgrades to CD are currently provided and are now supplied in grey livery only.

SE and IT systems were initially fitted with version 15 software and thereafter version 16. CD systems are supplied with N1 software. Customers may purchase either a basic system which offers all the V16 features plus additional system short codes, or they may purchase a CD system with the optional, chargeable Analogue Private Signalling System (APNSS) feature. This is a version of the Digital Private Signalling System (DPNSS), whereby speech is carried over analogue circuits controlled by a low speed common signalling channel. The Monarch CD Range Planning Handbook and SICAM Handbooks contain full details of APNSS.

Upgrades to earlier Monarch systems are also available.

All systems are single processor controlled except for the IT440 and CD440 (DP) which provide additional features, e.g. dual processor working, integral standby power and an optional data switch.

The table below gives the systems capacities but the figures quoted may not all be achievable simultaneously. For capacities of upgraded systems and those fitted with APNSS, refer to the appropriate Planning Handbook.

120A                  120          32            NA           32        1
120B                  120          32            NA           32        2
120B Compact          120          26            NA           12        2
SE120/CD120           168          32            20           12        2
250C1                 252          64            NA           38        2
250C2                 252          64            48           38        3
SE220/CD220           232          64            48           64        4
SE250/CD250           252          64            48           64        4
SE440/CD440           440         128            48          108        4
IT440/CD440   (DP)    496         128            48          108        4

Made by BT Communications Systems Division (CSD) using various subcontractors (GEC).

Distributed by BT Communications Systems Division (CSD) via BTUK Districts.

Facilities - As detailed in Private Exchange Master List (PXML) 85. CSI No 102 gives details of PXML Distribution and use.
Software and Hardware - approved hardware and software is detailed in PXML 85. Details of hardware and software changes will be published in Customer Field Notes initially, then transferred to the "Monarch Software releases and Hardware Enhancements" handbook.

Dump the customer database if necessary (due to customer MMI changes) and check filters are clean during a site visit at least once a every 6 months.

Customer database is stored on a RAM/NVM child board in EPROM. 176K RAM/NVM batteries have a life expectancy of 10 years and no routine change out is necessary. Check the RAM/NVM "Battery Low" LED on every maintenance visit.

On systems fitted with other than 176K RAM/NVM, the RAM/NVM battery should be replaced every 5 years.

The provision date, or last change date of batteries is shown on a label affixed adjacent to the battery or on the battery itself.

Support for each generic in the Monarch range will be available for a period of at least seven years after the last system is sold.

Exchange Line:
32 Port shelf cards:                          Normal: +5v B, -llv A
                                              Seize: Earth B Dis A
                                              Hold: Loop

96 Port shelf cards:                          Normal: +5vB, +5v A
                                              Seize: Earth B Dis A
                                              Hold: Loop

DDI Line:                                     Normal: -5Ov B, Earth A
                                              Seize: Not applicable
                                              Hold: Not applicable
                                              Back Busy: Open Circuit.

Monarch Kit 650
The "chip changing" technique may be used to update or change firmware on certain units. This is achieved by using a Kit 650A, B or C with associated handbooks.

Database Reprogramming
A database reprogramming service is available from Monarch Configuration Centres.

N1 software and Upgrades
For details of Monarch upgrades and the new facilities offered by N1 software.

There is also a featurephone called the TX72 that can be used with all Monarch systems.

The Monarch console was designed by DCA Design Consultants.

Introduced in 1980.

Monarch IT440

British Telecom (BT) Business Systems new Merlin Monarch IT440 introduces a new era of voice-data-text communications.

Based on the successful Monarch telephone system, of which over 10,000 units have been installed, and the experience gained with the UXD5, BTís small public exchange system, the IT440 builds on this to provide a system that brings business communications and computing closer to the reality of convergence.

The new system, developed by BT engineers, provides voice switching for up to 440 extensions and flexible data and text switching for up to 240 users. The design is modular so that the system can grow to meet specific needs; this modularity also means that voice and data switching are kept separate to avoid data traffic affecting voice switching, and affords greater security to both voice and data traffic.

The Monarch IT440 uses the proven hardware technology from the Monarch 250 allied to the dual-processor control
system from the UXD5 to provide an advanced voice switch.

This, together with stand-by batteries and zoned power supplies, ensures security of operation for the voice switch.

The stand-by batteries and power supply are also based on the experience gained with the UXD5 and with System X, and are installed in a cabinet en suite with the switching equipment. Regulatory requirements state that telephone systems with direct dialling-in must have a stand-by power supply, and this requirement is met by the power cabinet on the 11440. The equipment is housed in three cabinets, and an additional free-standing connection frame provides all extension and line cabling facilities.

The data and text switching facilities use the combined features of Merlin DatelNet 500 data-over-voice transmission
equipment, which allows full duplex speech and data transmission over ordinary two-wire PABX extension cabling, and Merlin Datelmux 5500, which provides the data switching capability. Terminal-to-terminal data or text switching uses named calling between terminals, and integral modem access provides ease of conversion for communication over analogue circuits.

The new system can have up to four operator consoles and offers improved call-logging information, which, when combined with the new Merlin CM8000 Call Management System, enables full details of public and private voice network calls and internal calls to be recorded.

The Monarch IT440 represents a significant advance in business switching systems whilst using proven technology. It
therefore provides a low-risk route to companies wishing to progress to integrated systems.

Existing Monarch 250 users will also be able to benefit from the development of the IT440. A sister version, the Monarch SE440, which will be available later in 1985, will enable Monarch 250C1 and C2 users to enhance their systems to the same size and software capability as the IT440, but as a single processor version and without integral stand-by power and data switching.

Taken from British Telecommunications Engineering, Vol. 4, July 1985



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Last revised: November 23, 2021