GEC PABX 4+24

4 + 24 line, extensible to 16 + 48 line
private automatic branch exchange

STANDARD FEATURES
Maximum capacity
Choice of 4 public-exchange lines and 24 extension lines, or
12 public-exchange lines and 23 extension lines, or
8 public-exchange lines and 49 extension lines, or
16 public-exchange lines and 48 extension lines.

  Individual extensions can be prevented from dialling public exchange calls.  
Incoming:
through operator's switchboard.

Enquiry and transfer
Telephones with a pushbutton can be supplied* to all or selected extensions to enable a public exchange call to be held while the user calls another extension with an enquiry.  When the enquiry is complete, the original extension returns to the public-exchange call, or can transfer it to another extension or to the operator.

Night service
Incoming public-exchange calls can be answered from any extension by dialling '8'; alternatively, the feature can be restricted to one extension only*.  Calls can then be transferred to other extensions by the enquiry and transfer method.

Trunk offer
The operator can offer a public-exchange call to an extension already engaged.

OPTIONAL FEATURES
Tie lines
Normally up to 2 for 24 extension lines and up to 4 for 49 extension lines, on one route only, at the expense of public-exchange circuits.

Conference  
Designated extensions can be connected together via a special circuit.

Fire-alarm*  
Various procedures are available to suit individual requirements and local fire regulations.

Staff Locations*
Staff absent from their offices may be called by dialling a special locating number and a personal code, to operate lamps or bells.

Secretary service
A secretarial switching telephone enables secretaries to filter calls to an executive.

Route restriction:1
Individual extensions may be permitted to dial local but not long-distance calls.

Mains-fail protection*
Public exchange lines can be automatically connected to designated extensions in the event of an AC mains supply failure.

GENERAL
Mode of operation
Fully automatic operation using 2-motion selectors, uniselectors and relays.  All conversations secret from each other

Tones and ringing
All-electronic tone generator provides dial tone, ring tone and current, busy tone, number-unobtainable tone and operator intrusion tone.

Signalling
Required dial-pulse characteristics: 7 to 14 i.p.s., 2:1 break to make ratio.

Alarms
Lamp indication at switchboard.
Urgent: release alarm, ring fail and blown fuse.
Deferred: failure to replace receiver (PG condition).

Power unit
AC power unit: input, 100 to 120V or 200 to 250V, 50 to 60 Hz single phase; 50V d.c. output 5A for 4 + 24 line, 10A for 12 + 23 line and 8 + 49 line, 20A for 16 + 48 line.
or
Battery: 50 V; with float charger, input as for AC power unit, 50 V d.c.

Line-loop resistance
Not to exceed 900 ohms.

Construction
Switching equipment: Plug-in and wired-in units on a steel framework in a floor-mounting steel cabinet (painted grey) with lift-off dust-proof panels front and rear.
Switchboard: cream and green desk-mounting console.

Dimensions and weight

4 + 24 line exchange = 1 module; 12 + 23 line exchange = 2 modules;
8 + 49 line exchange = 2 modules; 16 + 48 line exchange = 3 modules

*To be specified when ordering

1972

GEC Telecommunications Limited

A Management Company of The General Electric Company limited of England

Last revised: 18 November, 2000