In order to guarantee 100% no reduction in sync and throughput speed you would have to put the router as close as possible to the new NTE5 then run the extension as an ethernet (data) connection to your computer. If that is not convenient then the adsl signal together with the filtered voice signal sent along 2 pairs of a cat5 to a suitably located dual socket would probably minimize any loss of sync. That would require a filtered faceplate on the nte5, such as the pressac
http://www.amazon.co.uk/Pressac-NTE5-compatible-filt... with the adsl connected to the A&B terminals and voice connected to the 2&5 terminals on the back of the faceplate.
Alternatively, you could run unfiltered voice and adsl along one pair of the cat5 from the master NTE5 to a filter/splitter socket on the other end of an extension but that perhaps might not be so good.
Sorry I still feel uneasy about your intention to mess with the existing master nte5 since BT/OR engineers might still need to check your current wiring...
Edited by 4M2 (Thu 17-Nov-11 16:35:58)