BPO Private Manual Branch Exchange
(PMBX) MENU


General information and description of PMBX's

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NT SWITCHBOARDS Single Cord type
NT SWITCHBOARDS Double Cord Type
SECTION SWITCH BE CB No. 9
SWITCHBOARD AT 711
SWITCHBOARD AT 1800
SWITCHBOARD AT 1810 - (Automatic variant of CB887)
SWITCHBOARD AT 1837 - (1+1)
SWITCHBOARD AT 3718
SWITCHBOARD AT 3796 - (10+30/50/60)- (10+30/50/60)
SWITCHBOARD CB 723 - (2+2 Wall Pattern)
SWITCHBOARD CB 873 - (5+20 Floor Pattern)
SWITCHBOARD CB 884 - (10+10/20+20 Wall and Table Pattern)
SWITCHBOARD CB 887 - (10+30/50/60 Floor Pattern)
SWITCHBOARD CB 935 - (Cordless on CB and Auto systems)
SWITCHBOARD CB 1084 - (2+2 Wall Pattern)
SWITCHBOARD CBS 76 & 77 - (Admiralty System)
SWITCHBOARD CBS 364 - (Cordless on CBS No. 1 systems)
SWITCHBOARD CBS 484 - (Cordless on CBS No's 2 & 3 systems)
SWITCHBOARD CBS 488 - (Floor pattern on CBS No's 2 & 3 systems)
SWITCHBOARD CBS N934 - (Cordless)
SWITCHBOARD LD 70 - (Magneto System)
SWITCHBOARD N 1070 - (10+30/50/60)
SWITCHBOARD RP3751 - (Exchange speaker system)
SWITCHBOARD TL597
PMBX No. 1
PMBX No. 2
PMBX No. 3
PMBX No. 4
PMBX No. 11
PMBX No. 12
Abbreviations

A.T. - Automatic
B.E. - Branch Exchange
C.B. - Common Battery
C.B.S. - Common Battery Signalling
D.C. - Double Cord
F.P. - Floor Pattern
L.B. - Local Battery
N.T. - National Telephone Co.
S.C. - Single Cord
T.E. - Telephone Exchange
W.P. - Wall Pattern

How P.M.B.X.s are described:-
They are generally described by the main circuit diagram followed by a fractional suffix representing Equipment/Capacity.

E.G. Switchboard CB 873 3+10
                                           25
CB 873 is the main circuit diagram.
3+10 is the equipment/capacity of 3 exchange lines and 10 extension lines as supplied.
25 is the ultimate total capacity of 5 exchange lines and 20 extensions lines.





 

 
 
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Last revised: December 23, 2021

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