telephone wiring - is color meaning somthing?

Is there a rime or reason with telephone wire colors coming into the house? Not sure if all wires coming in need to be connected to the phone junction box? Appears that only red wire has voltage and green wire is return or ground? Found red wire has good power when I connect a test light to house ground and shows bright. When I connect ground wire of test light to other incoming wires no light is indicated. I have AT&T and the said the wires coming to the house are good. The phone works for out going calls but rings once for incoming then quits. Computer internet also quit working. Have numerous jacks but the house has in wall wiring and not all are consistent in colors. Some have been disconnected over the years. I would like to re-connect some of them.