Phone Jack wiring help

A phone line requires only 2 wires. A cable with 4 (or more) wires can support more than one phone line.

Traditionally, red and green are used for the first line and black and yellow are used for the second line.

Most phones come wired to use the red and green line. If you wanted the phone to connecet to the other line, you'd have to change the wiring of either the phone or the jack.

The funny wiring you found where the black and yellow were attached to the red and green terminal would have allowed an unmodified phone to be plugged in there, but it would have been connected to line 2 (if I followed your description correctly).

The second line might have been used for voice, a fax machine or a dial-up computer modem.

What RAL said.

In the olden days :vs_laugh:, the wires beyond red and green were also used the give a light, as on the famous Princess phone in every bedroom.

Wiring like to like is your best bet and if you get a dial tone, good to go.

Notice however, the jack wiring you may be using. The curly one too. Look carefully at an end. There may be only 2 wires (as in green and red). In that case, a second line would not work if it were a 2 line console phone.

So wherever there's 4 wires that are 'live', today it is likely that 2 lines are being supported.

Another olden days tip :vs_laugh::vs_laugh:: If you're still hooked to a copper service, keep an old wired phone handy (not cordless) for use during a power outage. The current in the red and green is enough to give you dial tone.