re help with phone wire which ones are tip ring in article apr husc harvard edu mlevin husc harvard edu michael levin writes i just bought a little gizmo that is supposed to be installed in series with the tip or ring lines of the phone wire which ones are those suppose i am holding a regular phone wire such that the little plastic tooth on the little plastic square thing with the naked lead ends that you plug into the phone is facing down and away from me which of the wires that i see is the tip and which is the ring please reply to mlevin husc harvard edu mike levin mike ring is the red wire tip is the green wire of most standard phone lines they two constitute the two wires most often used for voice telephone the two live lines they are the two innermost connectors of an rj phone jack another way of telling is that if you measure voltage from red to green ring to tip tip green being at ground potential of the voltmeter it should read volts in the on hook no ring position i am sure it s v and not volts doesn t hurt a phone too much if they re reversed it s just bad if one happens to somehow get grounded to earth ground elsewhere additionally when off hook the voltage drops to about to volts dc i think it is supposed to correspond to a to ma current loop and lastly when ringing the two wires develop an ac potential of about v p p at to hz across them where you get the electromechanical old fashioned bell ringer from hope that clears things squish endor harvard edu
