DIAGRAM INFORMATION
SYMBOLS
All BPO diagrams and line plant plans consist of symbols.  Most are just related to the telecommunications industry, although some are general electrical symbols.

Use the relevant links below to help identify specific symbols on the following subjects:-

AT/ATE DIAGRAMS
LINE PLANT
RELAYS
SELECTORS - OLD SYMBOLS
SELECTORS - NEW SYMBOLS
SELECTORS - TRUNKING
TELEPHONY 1
TELEPHONY 2
TWO MOTION
UNISELECTOR
WIRING - CONNECTIONS
WIRING - TWISTED BUNCHES


Rules and conventions on GPO diagrams
Symbols used on early telephone equipment - 1920's

 

 
 
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Last revised: July 25, 2025

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