Foreign Telephone Wiring

[john9159]

I have an old 'phone to bring up to modern standards such that it can be plugged into a BT socket.
The 'phone was originally used in Iran and has three wires - Black, Yellow and Red.
I gather the terminals to connect to on the 431A plug are 2 and 5 but which of the three wires do I connect?

Thank you

ps - haven't a clue in which forum this subject goes so took a chance on this one.

[TheNorm]

Maybe Black and Yellow (2 and 5), as per the diagram after "pinouts":

http://en.wikipedia.org/wiki/Registered_jack