First lets identify an external NTE :-

The customer side wiring can easily be seen on the right hand side.
To make the most of your broadband connection you need to trace the FIRST line box on the cabling that comes from the external NTE. Then simply connect the wires from 2 & 5 on the external NTE to A & B on an NTE5 socket :-

http://www.run-it-direct.co.uk/BTsocketNTE5.html
You can now install an ADSL faceplate and any other extension wiring as normal.
This means your ADSL signal is seperated from any internal wiring & will give the best possible performance. You also have the added benefit of no unsightly plug in filters around the house.
If you can not plug your modem/router into the new NTE5 then simply use an NTE2005 or XTE-2005 clone faceplate and run a dedicated ADSL extension from the faceplate to where your modem/router will be. The BT NTE2000 ADSL extension kit is ideal for this and because your ADSL signal is seperated from internal wiring any performance drop off will be minimal if at all existant!
http://www.run-it-direct.co.uk/BTNTE2000EX10M.html
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