What do the different colors on telephone wires mean?

[valentena]

Generally speaking the phone company connects the phone lines at their termination block in a certain order. The blue pair is first, the orange pair is second, the green pair is third, and the brown pair is fourth. So for one phone line, the blue pair should be the correct line to connect to.

[ChrisB]

You colours are accurate for a 4 pair cat5 cable.
Your picture is for the old four wire phone cable.

[valentena]

Thanks ChrisB for your response.