private automatic branch exchange
4 public-exchange lines and 24 extension lines; can be
extended to 8 public exchange lines and 49 extension lines.
Provision for 4 simultaneous inter-extension calls for
24 extension lines, and 8 for 49 extension lines, in addition to a maximum of 4
or 8 public-exchange calls.
Within the range 21 to 69 for extensions; 7 for
tie-line access; 8 for night service; 9 for public-exchange access; 0 for
Public exchange service
Outgoing: direct access from extensions, or through
operator's switchboard. 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.
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.
The operator can offer a public-exchange call to an
extension already engaged.
Normally up to 2 for 24 extension lines and up to 4 for
49 extension lines, on one route only.
Designated extensions can be connected together via a
Various procedures are available to suit individual
requirements and local fire regulations.
Staff absent from their offices may be called by
dialling a special locating number and a personal code, to operate lamps or
A secretarial switching telephone enables secretaries
to filter calls to an executive.
Up to 4 telephones without dials may be wired direct to
the operator's switchboard for special priority services.
Individual extensions may be permitted to dial local
but not long-distance calls.
Public exchange lines can be automatically connected to
designated extensions in the event of an AC mains supply failure.
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
Required dial-pulse characteristics: 7 to 14 i.p.s.,
2:1 break to make ratio.
Lamp indication at switchboard.
Urgent: release alarm, ring fail and blown fuse.
Deferred: failure to replace receiver (PG condition).
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 8 + 49 line.
Battery: 50V 32AH ; with float charger, input as for AC
power unit, 50V d.c., output 3A.
Not to exceed 900 ohms.
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: dual grey desk-mounting console.
|4 + 24 line switching
||209 cm (82 in)
||51 cm (20
|8 + 49 line switching equipment PB2649
||51 cm (20
||31 cm (12 in)
|A C mains unit SU3203 (4 + 24 line)
||24 cm (19 in)
|A C mains unit SU3204 (8 + 49 line)
||39 cm (15 in)
|Float charger SU4203
||24 cm (9
be specified when
A Management Company of The General Electric Company
Limited of England