(quoted from post at 20:13:44 09/22/14) The red/green/yellow/black wire is obsolete. Why it does support plain old telephone service, it does not support any digital, dsl, adsl, isdn, or other services. This wire also did not correctly support two lines as the ringing tone on line one could bleed over to line two. this type of wire had NO twist and therefore was prone to bleed over, crosstalk and data bleed off. Phone companies quit using the old wire in the 70's and switched to cat3 wire. Cat 3 wire will have about 3 twists per foot for each pair of wires so they they never run side by side with the second and third pairs continuously and therefore any crosstalk is canceled out by the twists. Cat 3 will usually be blue/ bluewhite, orange/orangewhite, green... brown... slate...etc etc..
the tip and ring designation refers to how the wire connected to the old cord boards.. the plug for each line consisted of a tip, ring, and sleeve. the sleeve was a ground to the talking was on the tip and ring.. the operator would then plug that cord into the jack to answer the call. The ring is always on the right, always ridged, always red, is the old rules...
(the tip is the left binding post, and the striped wire or non solid color wire.) The solid color replaced the red wire, so a bluewhite/blue wire, the blue would be the ring and the blue/white would the the tip wire.
