I'm trying to connect a new extension cable directly into a 40 years old GPO box which is the only telephone connection into my house. The GPO wires are orange, white? and green in that order from top middle and bottom. The new cable has 4 wires, black, red, green and yellow.
There is an extension already attached which provides my phone into another room but the wire colours seem just as old. It has orange connected to orange, blue connected to the whitish cable and green attached to green. It has an unconnected brown also.
Can anyone please help? How can I tell which cable gets connected to which? I have tried a few different ways and can connect but my bb speed is reduced to a third of normal.