PABX PB 8000
Private Automatic Branch Exchanges
The PB8000 is an extensible register-controlled exchange intended to serve medium-to-large organisations. With minor variations it caters for 100 to 8000 extensions and provides the latest facilities, including press button signalling and 'cordless' operation of its manual switchboards. Depending on the size and traffic requirements, the PABX employs a four or five-stage switch network based on the proven Plessey 5005 crossbar switch. The exchange has a high traffic-handling capability of 0.2 erlang bothway traffic per extension. No limit is imposed on the number of exchange or inter-PBX lines required.
High quality speech/data transmission. Flexible numbering.
Attractive equipment units.
Easy-to-operate switchboard consoles.
Switchboards: single, back-to-back or 'en suite' installation.
Unrestricted - Full traffic facilities within the national network.
Preference (or Priority) - Full traffic facilities including Direct International Subscriber Dialling (DISD) and intrusion into established extension-to-extension calls.
Trunk barred - Direct-access external calls limited to 'local-fee' areas.
Barred direct access - External calls originated and received via the PABX switchboard only.
Fully barred - Internal calls only.
Assistance calls to the operator.
Inter-PBX calls obtained automatically or via the operator.
Direct access to the public exchange by keying a single digit, e.g. '9'.
Hold for enquiry by pressing the enquiry button once, enabling an extension to hold an established external call while making an enquiry call to another extension. Automatic transfer by the originating extension of an established enquiry call to the called party on handset replacement. If misoperation by the originating extension occurs the external call is automatically transferred to the PABX switchboard.
Operator recall by successive keying of the enquiry and assistance digits. A second operation of the enquiry button returns the extension to the external party.
Through clearing via both automatic equipment and switchboards.
Forced release of calling party 20 seconds after release by called party.
Discriminating ringing to differentiate between internal and external calls.
Lamp and tone supervision of call progress.
Automatic release of established calls, with optional supervisory hold facility.
Ring-when-free condition applied automatically on calls from the PABX operator to engaged extensions.
Call splitting on external calls, enabling the operator to speak to called or calling parties in secrecy.
Call release by the operator on calls answered at the switchboard but not extended.
Route-busy indication by illuminated outgoing group button or display of the numerical identity of engaged route.
Numerical-identity display of faulty operator associated circuits.
Audible and visual indication of incoming calls.
Extended prompt/deferred alarms from the automatic equipment.
Register capacity of 18 digits.
Standard ringing and tones.
Standby ringing machine.
Line lockout occurs if a call does not proceed within the permitted time after handset pick-up, or if a caller fails to clear at the end of a call.
Night service enables incoming calls, during the night-service period, to be either routed to selected extensions or to ring special bells and be answered by any extension keying the appropriate digit, e.g. '8'.
Transit switching of inter-PBX calls by connecting an incoming call through the exchange to an outgoing line.
Call-count metering for traffic analysis and maintenance.
Out-of -order or test-and-busy cabinet.
Alarm panel on the automatic equipment gives audible and visual indication of any fault adversely affecting the operation of the exchange equipment.
Line test case with Keyset, meters and indicators, etc., to facilitate the detection of faults on lines and circuits within the PABX.
Register store tester.
Equipment monitor for print-out of switching stages and relay groups involved in equipment failure, together with details of the fault.
Calling-extension line identification
Direct dialling-in (DDI)
Satellite working, with PB8000 as main exchange Equipment congestion recording
Staff calling (various systems)
Data transmission and capture Short-code dialling
Automatic call diversion
Program control of extension numbering scheme
Automatic call back
Program control of class-of service options.
External number repetition
Dust covers along the base of the suite pivot forward to give access to the fuses.
On the face of the switchboard are number displays, meters, press buttons and lamps. For simplified operation and space economy, control press buttons have in-built supervisory lamps and simple press-to-release or non-locking actions. A press button Keyset is provided for rapid handling of calls.
Switchboard dimension (approx.)
Ringing and Tones
Inter-PBX line limits depend on the type of signalling used and maybe greater than 1000 ft.
PUBLICATION No. 7651, 4/76
Last revised: October 10, 2019