Old Rotary Telephone Connection

[Kevin]

I recently bought a very old rotary telephone, and I would like to
hook it up and use it. There are 3 wires in the telephone cord--red,
green and yellow. How do I hook these wires up to a standard RJ11
jack? The phone I have has red, green, yellow and black.

Is there something else I need to modify to get this to work?

thanks! Kevin