a single pair connects to the very back of the NTE5 - in the past a pair of screw connections, new ones are IDC.

I'm not clear if the incoming line is actually split externally or if it's backwired to the split, I haven't concentrated enough. If there is a single incoming pair to the back of the NTE5 and a phone works in the test socket with no other sockets "live" at the time (faceplate off) then its ok.

If two (or no) sockets are live with the NTE5 faceplate off then it's wrong.

It seem the line is not split outside as you had originally thought , but that the upstairs 'extension ' is back wired from the downstairs master socket on a second pair on the downstairs lead in, then joined to the upstairs lead in where it then goes to the upstairs socket.

Backwired?

In reply to a post by broadbanddoomed:

Took faceplate off downstairs and line upstairs is dead

A pair in dropwire to the downstairs NTE is feeding the upstairs socket "backwards" ie service is going up the last bit of the drop wire (yes I know it's bidirectional, think in terms of exchange to phone)

Yes, the incoming exchange line is using one pair of the downstairs lead in to the master socket, then another pair in the same lead in is used to connect to the faceplate and send the extension side back to the external joint, where it is crimped to the upstairs lead in, feeding the extension socket.

Got to give my thanks to everyone here on this forum for the really useful analysis. Way beyond what I expected. There's no way the girl in India could have helped with this.

The two wires connecting to the faceplate of the master socket have those two transparent connectors and I don't see why I can't just take out the wires from these two connectors that lead to the faceplate? see second pic http://www.flickr.com/photos/11245340@N00/sets/72157...