There is only two wires connected to A and B because that is all BT use.
The ring wire is whatever is connected to pin 3. Hard to say much more without seeing pictures of the wiring, e.g take a few and put them on flickr
Reason for saying this, is I don't understand how you can be using the test socket with a ring wire connected, by definiiton if the master socket is first socket, then once the removeable faceplate has been removed there is no ring wire connected anyway.