PXML No. 43
APPROVAL No. NS/1412/GF/1981/PR & NS/1000/GF/1981/PR

Click here to see information on BT's withdrawal of Subscribers Private Metering (SPM)

'Regent' is the BT marketing name for the Mitel SX200.  Marketing names used by non-BT suppliers may be SX200, ROYALE, SUPERSWITCH. (SX200 with 247 console)

The SX200 is 256 port Call Connect System (CCS), of which 184 ports are available for assignment to extensions, trunks and private circuits (the remainder are used for receivers, special functions and the common control). The systems capacity depends on how these ports are used, as an extension uses one port, a trunk uses two ports and a private circuit uses four ports.

The maximum size of the system is actually 24+134.

Regent is an SPC switch utilising CMOS switching and a MC6800 CPU supported by 8k of RAM. The generic (system operating programme) is stored in 56K of programmable ROM and there is also 4K of battery backed up RAM that contains access code and extension information.
Speech is analogue using 31 speech paths connected to every port on the system.

The system is housed in a floor standing cabinet of size 960 mm high, 600 mm wide and 700 mm deep and weighing 132 kg when fully equipped.

Various generics are approved:-
Generic 245 (these had white consoles)
Generic 345 (SX200, non-BT supply only. Cannot support supersets/TX14).
Generic 247 (these had black consoles)
Generics 248/250 are approved (non BT).
The Customer database is held on battery backed RAM on the Integrated Processor Control Card.
G245 customers cannot change data base (thumbwheels inside cabinet) Other generics have default database and limited programming by customers.

Extension cards contain eight ports, trunk cards 4 ports and private circuit cards two ports. The system also supports TX14/Superset 4 featurephones that operate on special extension cards.

Introduced into the UK mid 1982 and initially available only in BT regions BTE, BTNW and the City of London.

The SX200 is sold through a number of distribution routes in the U.K. and as a consequence may be badged as follows: Casstel, Royale, SX-200 & Regent.

Made by Mitel Telecom Ltd. Severnbridge Industrial Estate, Portskewett, NEWPORT, Gwent. NP6 4YR
Telephone 01291 430000

For liberalisation purposes, the equipment is classed as an analogue PABX.
Approval has been granted for a networking arrangement for multipled SX200s. Each networked site is granted specific connection approval by Technology Applications Division.

Batteries on memory/IPC cards require renewal every 4 years. As later cards have hard wired batteries, this will necessitate returning the card to MITEL. System standby battery, if fitted, also requires renewal every 4 years.
NB: Due to the possibility of batteries rupturing, hence causing leakage, it is essential that the renewal period of both types of battery are strictly adhered to.
Remove or switch off RAM batteries from memory cards prior to transportation and use the appropriate antistatic bags (the clear type are only conductive on the outside and should be used in this instance).
The PSU (back door) and Standby Battery Pack are extremely heavy to lift and install by one person!

This instruction describes the 245 variant

3 Internal
Issue 2, Mar 1982




This TI provides a description of Regent. Other related Regent TIs are:-

Regent Call Connect System - Installation Planning F3022
Regent Call Connect System - Configuration F3023
Regent Call Connect System - Installation and Commissioning F3024
Regent Call Connect System - System Connection Boxes F3025
Regent Call Connect System - Maintenance E5 D2160
Regent Call Connect System ~ Sales Overview B4 F4020
Regent Call Connect System - Sales Procedure B3 B0071

Further detailed information is given in:-
ITEM CODE DESCRIPTION 37 3841 Regent Handbook 9110-032 (2 Volumes)

Regent is an electronic PABX using digitally controlled space division switching and stored program control.

The system capacity is 256 ports. 184 ports are available for assignment to extensions, exchange lines and private circuits. The remaining ports are used for receivers, special functions and the common control.

An extension uses 1 port, exchange line 2 and private circuit 4.

For BT use the maximum size of system is normally 24 exchange lines, 136 extensions. 2 of these extensions are reserved for BT maintenance use. The maximum number of connections possible at any time Is 31.

A system is built to customer order size by the provision (or removal) of Apparatus Slide-in Units (ASUs). Extension ASUs have 8 circuits, exchange line ASUs 4 and private circuit ASUs 2.

At present software operating program codes generic 245 is standard, other generics offering different facilities may be introduced. Generic 245 facilities are listed in Regent Handbook 9110-035 Volume 1 Section MITL9110-98- 105 (BT).

Circuit malfunctions are detected by diagnostic routines automatically initiated by the Central Processing Unit (CPU). Together with the functional packaging of the equipment these routines will in most cases locate faults to a particular ASU. Preventative maintenance is limited to the occasional replacement of memory protection and (if provided) standby power unit batteries.

The equipment cabinet is 965 = high, 600 mm wide and 700 mm deep. Fully equipped with ASUs it weighs 132 kg.

The front door of the equipment cabinet gives access to the maintenance panel, ASUs and standby power supply shelf. The rear door holds the system power supply and gives access to the connectors used for linking the system to a frame, emergency switching circuitry and the standby power controls. Cable entry is through holes at either side at the bottom of the cabinet.

Maintenance Panel
Mounted at the top inside the front of the cabinet. A connector is provided for a maintenance console. The the left of this connector are the emergency switching control switches. On the extreme left are terminals for a test extension.

Maintenance Console
Allows system access for maintenance tasks and entering new, or modifying existing customer configuration data.

Equipment Shelves
Equipment shelf 2 is directly underneath the maintenance panel. Equipment shelf 1 is below equipment shelf 2. Equipment shelf 1 holds a maximum of 22 ASU's. ASU slots are allocated to common control ASU's, console control, tone and receiver ASUs and some extension ASU's. Equipment shelf 2 holds a maximum of 14 ASU's, extensions, exchange lines and private circuits. Lines are extended from the equipment by connectors plugged into the rear of the equipment shelf backplanes.

The system primary power supply is mounted on the back door of the equipment cabinet. 240v 50 Hz mains power input is converted to the voltages required by the system. The optional standby power unit is contained in a completely enclosed shelf assembly which fits beneath equipment shelf 1.

Console - 245 model Console - 247 model

Operator Console
The console keyboard (shown above) has 3 rows of 10 non-locking keys for selection of facilities and control of calls. To the right of the keyboard is a push button keypad. The console display, mounted above the keyboard displays the state of calls in progress. There is a busy lamp field, a trunk group status display, a call waiting indicator, a digital clock and 3 alarm indicators. The console is connected by plug ended cable to the equipment cabinet.

Emergency Switching Circuits
12 circuits which connect exchange lines through to standby equipment or dedicated extensions are mounted on a printed wiring assembly fitted in the back left hand side of the equipment cabinet. These circuits are extended from the cabinet by plug ended cables.

Extension ASU
8 circuits which interface extension apparatus to the PABX interconnecting speech paths via a switching matrix mounted on the ASU.

Exchange Line ASU
4 circuits which interface the lines from the serving exchange to the PABX interconnecting speech paths via a switching matrix mounted on the ASU.

Receiver ASU
2 circuits which can detect both 10 pps and ssmF4 signals from extensions and transfer them to a temporary store during call processing.

Console Control ASU
Interface between the switching matrix and common control for 1 operator console and 1 maintenance console.

Tone Control ASU
This ASU supplies all call progress tones and houses dial pulse generators, voice paging circuitry and diagnostic testing functions.

Scanner ASU
Sequentially scans all parts to detect signals which require processor action. Also contains the night bell and paging control relays.

Contains part of the system operating software in a PROM daughter ASU which plugs onto the CPU ASU. The CPU ASU contains the system controlling microprocessor and associated circuitry.

Contains RAM store for customers abbreviated dialling and call barring information. A battery is mounted on this ASU which will retain RAM information during power failure.

RAM for customers configuration data and call processing transient record. A battery is mounted on this ASU which will retain RAM information during power failure.

Private Circuit ASU
ASUs to provide SSAC13, SSAC15, SSDC5 and Loop bothway signalling, 2 circuits per ASU are available. An externally mounted ASU to interface Regent mounted 2 wire SSDC5 to SSDC10 is available, 2 circuits per ASU.

Extension Originating a Call
Lifting an extension handset draws line current. This is detected by an operational amplifier on the extension ASU. A light emitting diode (LED) on the front of the ASU is illuminated and an off hook signal set for the particular extension. This signal, together with signals from the other 7 extensions on the ASU are presented to an analogue switch. The scanner, which is continuously examining all lines every 3.2 ms, addresses each extension via the IA bus. The off hook signal is presented on the IZ line for the particular ASU. The change of IZ line condition causes the scanner to stop scanning and interrupt the processor via the IRQ line. The scanner presents the extension, ASU address and the IZ line condition to the data bus which the processor reads while restarting the scanner.

Operator Console Originating a Call
The console does not generate an off hook signal. Provided that the handset is plugged in it is only necessary to depress the key of the first digit required.

Connection of Dial Tone To An Extension
When the processor recognises an off hook condition it interrogates RAM to identify a free speech path which it checks using the diagnostic circuitry on the tone control ASU. The tested speech path is then connected to the extension circuit. The processor searches for an idle receiver and then dial tone. The processor then connects the selected receiver and dial tone to the same speech path using the ASU select, address and data lines. Dial tone is heard at the extension.

Extension Dialling An Internal Number
SSMF4 or 10 pps signals from an extension are passed through the extension line circuit to a speech path and then to a receiver. The receiver detects either type of signal. SSMF4 is recognised using filter circuits, 10 pps pulses are decoded by a pulse counter. The receiver sets an interrupt signal and when the scanner addresses it, the interrupt is placed on the IZ line of the receiver ASU. The change on the IZ line causes the scanner to stop and to interrupt the processor via the IRQ line. The scanner presents the receiver and ASU address to the data bus which the processor then reads while restarting the scanner. The processor reads the digit from the receiver and disconnects dial tone from the speech path. If the processor determines that the digit is valid but does not completely define a number it stores the digit in RAM. If the digit is invalid NU tone is connected to the speech path. A valid extension number causes the processor to disconnect the receiver and to connect a tone generator to provide ringing tone to the originating extension. If the called extension is busy then busy tone is connected to the speech path.

Operator Console Dialling An Internal Number
The console keypad signals are recognised by a console microprocessor which examines associated ROM to identify an 8 bit code particular to the depressed key. This code is converted to serial data, with a start and stop bit and sent as a differential signal to the console control ASU in the equipment cabinet. The serial data is converted to parallel in the console control ASU. A data ready signal is presented on the IZ lead when the scanner addresses the console control ASU. The processor determines whether the digit is valid. For invalid digits NU tone is connected to the console speech path. If the digit is valid but not a complete number it is stored in RAM. If the digit is valid and complete the processor rings the extension and connects ringing tone back to the console.

Ringing An Extension
When the processor detects that a valid number is dialled it sends a command on the data line to the address of the called extension which switches on ringing current. When the extension answers the off hook signal is generated. Then processor disconnects ringing current and connects the called extension through to the speech path used by the calling extension.

The recall signal is detected by the extension ASU. The processor disconnects the extension from its speech path, finds a free speech path, tests it, and then connects the new speech path to the extension. A receiver and recall dial tone are connected to the new speech path and the extension is then able to dial other extensions or facilities. The other party of a call is connected by the processor to a 600 2 termination.

Incoming Calls
The exchange line ASU detects incoming ringing current. A microprocessor on the exchange line ASU interrupts the system processor via the IZ lead/scanner procedure and illuminates the exchange line LED on the front of the exchange line ASU. The system processor finds and tests a free speech path and notifies the programmed answering equipment (console or extension). When the call is answered the system processor connects the exchange line and answering equipment to the speech path. A command is sent to the exchange line ASU to terminate the trunk circuit and enable speech.

Dialling An Exchange Line From An Extension
An extension originating a call receives dial tone as described in 7.3. If the extension then dials the code for an exchange line the processor interrogates the exchange line ASUs to find a free circuit in the exchange line group. A data line seize command is sent to the selected exchange line microprocessor and the exchange line is connected to the speech path. The exchange line ASU connects an earth calling signal to the service exchange and waits for an acknowledgement signal. The exchange line processor enables the audio and illuminates the LED on the exchange line ASU. Serving exchange dial tone is received at the extension.

10 pps Extension Dialling Out
The subsequent dial pulses from the extension are repeated by a relay on the exchange line ASU and are extended to the exchange line. Unless discriminatory call barring is specified the receiver is disconnected when the exchange line access code is detected.

SSMF4 Extension Dialling Out
SSMF4 tones are translated by the receiver to digital data and passed to the system processor. The system processor adds further data and passes the information to the exchange line ASU processor. The exchange line ASU processor converts the data into a 10 pps pulse train onto the exchange line. The receiver is released when dialling is complete.

Operator Console Dialling Out
The console keypad produces digital signals which are stored by the console microprocessor. After an exchange line access code has been dialled the subsequently keyed data signals are forwarded to the system microprocessor for decoding and then on to the exchange line ASU for pulsing out on the exchange line. A receiver ASU is not used.

Operator Console Data Updating
All LEDS, including 7 segment displays on the operator console are refreshed or updated under the control of the generic software program every 100 ms. The status of each display element is maintained in RAM on the RAM/COS ASU. Every 100 ms, the system processor addresses the RAM on the console control ASU and sends it 64 bytes of information for each of the 2 consoles. This data is converted to serial form and forwarded to the console. In the console, the information is transformed to parallel data and stored in RAM. The console processor takes control of the information and sorts the data into a form required to turn on or off the LEDS. The console audible tone calling device is also controlled by this data.

Power information

On the backplane
wires on Connector TB1
Orange = +8v dc
Violet = -10v dc
Yellow = -5v dc
Brown = 0v
wires on Connector TB2
Grey = 90v ac
brown = earth
Blue = -50v dc
TB1 is top left
TB2 is bottom left
1 - -10v
2 - -5v
3 - 0v
4 - +8v
5 - +8v
1 - n/c
2 - 90v ac
3 -
4 - earth
5 - -50v
On the Emergency switching card
Located at the bottom inside rear left hand side.
1 - n/c
2 - Yellow - -5v
3 - Brown - 0v
4 - Orange - +8v
5 - Blue - -50v
6 - White/Blue
7 - Red
PSU terminal TB3
Numbered top to bottom
1 - batt
2 - 64v dc
3 - 0v
4 - -50v
5 - 75v ac
6 - 0v
7 -
8 -
Check with reference to the earth lug on the back door.
1 & 2 are linked and so is 7 & 8.

Description					Part No
1 SHELF CABINET	(SX100)				9110-001-003-BA
2 SHELF CABINET	(SX200)				9110-012-000-NA
IPC GEN 345					9110-203-345-NA
SCANNER CARD					9110-104-000-NA
TONE CONTROL CARD				9110-005-002-BT
REC CARD QUAD					9110-016-005-BT
EXCH LINE CARD 4 CCT				9110-311-011-BT
EXTN LINE CARD 8 CCT				9110-310-000-BT
E+M 2 CCT CARD					9110-313-001-BT
AC15 2 CCT CARD					9110-113-000-BT
RECEIVER CARD DUAL				9110-003-001-BT
AC13 2 CCT CARD					9110-213-002-BT
SCDC CONVERTER					9110-065-000-BA
CONSOLE 					9110-107-007-BA
CONSOLE J/F BOARD				9110-045-000-NA
STANDBY POWER					9110-014-002-BT
IPC GEN 247					9110-203-247-BT
E&M TRK CARD					9110-013-002-BT
EQUIP SHELF					9110-012-003-BA
VHOC KIT (SX100)				9110-070-000-BT
PS UNIT 240V					9110-308-000-BT
POWER FAIL TRANSFER				9110-023-000-BT
INTERCOM CARD					9110-124-000-BT
AC15 TRUNK CARD (G48)				9110-113-002-BT
AC13 TRUNK CARD					9110-213-000-BT
SUPERSET EXT CARD				9110-410-001-BT
TIE TRUNK CARD					9110-031-000-BT
INT CONNECT CABLE				9110-026-000-NA
Meter Pulse CD 12CCT				8170-000-000-BA
IPC GENERIC 250					9110-203-250-NA

In the case of G345 IPC Card faults, GENERIC 247 IPC Card may be
used as a replacement.



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Last revised: September 24, 2021