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Tip & Ring Nomenclature

The names for the two wires of a telephone line were derived from the electrical contacts on the original 1/4 inch telephone plug. These plugs are similar in appearance to the commonly used 6.5mm diameter stereo phono plugs

REF-tipring.gif

One electrical contact is at the tip of the plug (used for Line +) and the other is a ring just above it (used for Line -). There is also a third contact referred to as the sleeve.

Conventional nomenclature is:

TIP (note) A-wire Line (+) positive Earth Red
RING B-wire Line (-) negative Battery Black

 

Note: A useful memory aid is to remember "Red TAPE" :  (Red = Tip, A-wire, Positive, Earth