|PXML No. 102
APPROVAL No. NS/1000/3/E/450427
The Escort Call Connect System comprises a wall mounted Central Control Unit (CCU) and
extension telephones with associated key-modules individually cabled to the CCU. The CCU
contains a transformer type power unit, line termination strips, switching relays and
electronic control circuitry, it is similar to the TMC KBX 3
& KBX 6
CCU but is covered by a
separate approval and PXML (PXML 102).
The system is designed to accommodate up to 2 incoming trunks and up to 6 extensions. Incoming trunks may be Exchange Lines or PBX Extensions as detailed under 'Approval
Press buttons on the key-modules enable direct press button access to exchange lines and
other extensions, an additional button (Mode button) is also provided to facilitate
customer programmable facilities. LEDS are provided next to the exchange line buttons to
indicate status of exchange line. Key modules may be table or wall mounted.
The signalling system between the key-module and CCU is based on DC resistance conditions
applied to the signalling leads when the key-module buttons are pressed.
Optionally, extensions 1 and 3 may be used as (2 wire) extensions with restricted
External extensions are not available.
The system has only one intercom circuit, which is non-secret.
Introduced around 1986
CCU measures 320mm x 225mm x 85mm, approx. weight 4kg.
Key-modules measure 180mm x 155mm x 40mm, approx. weight 270g
Made by TMC Limited
CCU shown on the right
Approved for indirect connection to the PSTN (loop disconnect or MF4 signalling
depending on extension telephones fitted) by working as a (List 'A') subsidiary system
connected to a (List 'C') PBX.
The system supports Earth loop or 'C wire supervision' recall. Timed-break recall
facilities may be made available by providing 'timed-break recall' telephones on
Approved telephones (as of May 1986)
Approved software levels for Escort are:-
These levels are
marked on Custom I/Cs in CCU.
The system has a nominal power consumption of 30 watts and does not require a mains earth.
There is no provision for standby power.
Access to cable terminations and mains fuse is gained by loosening the two large screws on
the cover this will enable the lower half of the cover to slide down for removal. Mains
supply must be disconnected before removing the mains cable terminal cover or mains fuse.
The CCU is wall mounted by a flush fitting bracket and may be removed (when cabling has
been disconnected) by removing the cross-headed securing screw adjacent to the
configuration switches and lifting off.
It is not a maintenance responsibility to program Escort extensions. If extension
programming has been lost due to a fault condition, customers should be advised to
reprogram extensions when the fault has been cleared. If requested, maintenance engineers
should offer basic assistance to enable customers to programme their facilities.
When maintenance exchanging the CCU ensure that the internal switch settings
(SW1 - 4) are
set the same as in the unit it replaces. These switches are not customer accessible.
These switches are initially set by the manufacturer to OFF and the facilities
afforded by them are only active when in the ON position.
- CAN USE MANY STANDARD PHONES
- CAN PIGGYBACK OFF MOST SWITCHBOARDS
- HOLD + TRANSFER CALLS
- TRANSFER/DIVERT CALLS
- OPERATOR SERVICE FOR LIMITED ACCESS EXTENSIONS
- NON SECRET INTERCOM CIRCUIT
- EXCLUSIVE USE OF LINE “2”
- EACH USER MAY HAVE SECRET USE OF INCOMING/OUTGOING EXCHANGE LINE CALLS
- ENQUIRY CALLS OR SHUTTLE CALLS OR KNOWN AS BROKER CALLS ON THIS SYSTEM
- OPTIONAL LIMITED ACCESS FOR EXTENSIONS 1 + 3
- CONFERENCE CALLS BETWEEN EXTENSIONS OR EXCHANGE LINES
- MAINS POWER FAIL
- VISUAL LINE STATUS LAMP + BELL
- EXTENSION BELL
- EXTERNAL EXTENSIONS
NOTES ON FEATURES AND FACILITIES
- Most currently available in phones are suitable, prime examples are Statesman, Ambassador, Viscount + Venue 24; facility phones. Tonto and Tribune are
functionable but are found best to work within 100 metres from the CPU.
- Escort is ideally suited as a subsidiary system off a host PBX and would be useful as a particular departments system within an organisation; substituting the two exchange lines for 2
PBX extensions off the main host.
- All users could be capable of answering exchange line calls and passing on such calls to other extension users. If necessary they may hold an incoming call then summon the extension user and announce the caller before passing forward the call.
- A module station may wish to be undisturbed for a period of time and therefore arranges to transfer all its calls without interruption by means of a divert facility. The divert facility is fairly rigid, however and may only be effected as
Station 1 to Station 2
Station 2 to Station 1
Station 3 to Station 1
Station 4 to Station 2
Station 5 to Station 6
Station 6 to Station 5
Note if diverted calls are programmed to a 2 wire station i.e. one without a module then internal calls only are diverted. Exchange line calls may be reported to faults as “ringing tone no reply”. This is due to the fact that the two wire station has been given limited facilities and would not normally have exchange line access in its own right.
- To avoid call abuse some customers may opt for an “operator” type function for
1/3 of the extensions; these extensions are not fitted with Key Modules, therefore, they are automatically connected to extension 2 when the headset is lifted and all their intercom
& exchange line calls are set up and filtered back to them via extension 2.
- Warning Note - the intercom circuit is non-secret! Any station lifting its handset and preparing to make a call will be connected to an internal conversation which is already in progress; until they make their own intercom or exchange line call.
- On a 2 line exchange system the customer may allow extension 4 the exclusive use of the 2nd exchange line. Other users will see the line status of line 2 but may not access it. However, STN 4 may transfer line 2 to other extension users.
- Unlike Intercom calls, all exchange line calls/incoming/outgoing may be conducted in secret on all
- Enquiry or shuttle calls are available either between extension and one exchange line or between two exchange lines.
An extension with exchange line access may hold a call on one exchange line
and if the other exchange line is free make an enquiry call on that line at the same time. Alternatively the extension may hold the exchange line call
and enquire at another extension or shuttle between the two.
- Most of the extensions are fitted with Key modules and allow full system
and exchange line access. However, there may be some areas where call abuse may happen; in which case normal 2 wire
telephones are fitted without key modules and calls are made through the operator station 2.
Limited access stations must be stations 1 + 3.
- Conference calls may be set up between 1 exchange line and 2 extensions; the exchange line call may be incoming or outgoing. However, other stations may be brought into the conference by the originating stations making enquiry calls to other stations. Internal conference calls may be set up with as many as 4 stations.
- With mains powerfail calls will drop back to stations 1 and 4 on a two line system station 4 must be programmed so that this occurs. No other stations will be capable of receiving incoming calls during powerfail.
- All stations have a visual indication of line free/engaged. Each station also, at will may programme on or off the audible bell.
- Extension bells are compatible off all stations.
- External extensions are possible 2 wired limited access stations as directly wired/or possible indirect. 5 wired stations with Key modules should be surveyed; due to the network being 2 wire they would not be suitable as indirect.
CCU Switch settings
||Two wire working on extn 1
||Two wire working on extn 2
||C wire signalling
||Exclusive line facility on extn 4
LJU Wiring (Master)
CABLE WIRING COLOURS
The module extension keys are numbered numerically from left to right
omitting their own extension number.
e.g. Extension 2 would read: 1 - 3 - 4 - 5 - 6.
New units, either those supplied with the system or as maintenance spares carried a 24
month warranty from date of manufacture. The year and week of manufacture form the first
four digits of the eleven digit serial number marked on the base of the CCU or key module.
||BT Item code
|Escort Key Module
Idle - Normal capacitance loop.
Seized - Normal Tele loop when through to an extension.
Held - 260 ohm loop.
The Escort is approved as a non-earthed CRA and hence earth leads must not be
connected to the E tags of the exchange line terminal blocks.
Not recommended for use on host systems that give continuous ringing as Escort cannot trip
ringing during a ringing period.
With the lower cover removed, the upper cover may be removed by sliding outwards the two
small rectangular latches (one each side at the lower corners of the upper cover) and then
lifting the cover away. The upper cover needs to be removed to check PXML software and
hardware markings and date of manufacturer.
The ringing generator of the Escort System is designed to ring all six extension ports
simultaneously provided that the Ringer Equivalent Number (REN) on each port does not
Extension bells can therefore be fitted at extension ports where the telephone has a REN
of one or less.
Extension bells should be hardwired to terminals 3 and 5 on the extension phone socket.
Extension bells approved for use with the Escort system are:-
Bell 59D (High Impedance ringing device)
Bell 80D (incorporated in Bell Set 50C)
Fuses used on this system are BT type:- 36A/0.25