Evening guys. After following your instructions RobertoS and removing the faceplates, noting down which terminals were connected and by which coloured wire. I did a quick google and learnt something new which explains why the extensions have no dialtone

It's very embarrassing though but as I said, I didn't know, but atleast I do now!
I've had the router plugged into the test socket this whole time, and have just learnt that when you remove the bottom half of the master socket, it disconnects all of the extensions

Whoops! Glad I learnt that now rather than later though! Although that doesn't explain why we lost dialtone to all phones the week before, when I hadn't been anywhere near any of the sockets! Hmm the mind boggles!
All of the wires match up on each socket colour for colour. However, there is an extra wire connected on all of the sockets on T3 which is white with a blue stripe. Should this be removed? Will it do any harm being connected?
With my mistake discovered though, it still doesn't explain the insanely high ping which was getting worse and worse day by day. Although that seems to have been rectified by restarting the router, I'm worried it'll be a reoccurring event. And also why the router is syncing happily at 7616kbps but the IP profile is sticking at 4000kpbs. That said, I've decided I'm going to leave the router plugged into the test socket for the full 5 days to see if the IP profile changes in accordance with the sync speed, and I've plugged the base phone into the filter downstairs too so all of the phones now work just fine.
Would having interleaving switched off help at all? I've read it'll help lower latency so long as our line is stable, and from the stats we've always had I would think it should be fine to be switched off. I'm wondering if it would help shift what appears to be the stuck profile though as well. Any ideas?
I wish they'd upgrade our exchange! It's not been touched since 2006. Yet if we lived half a mile in any other direction (Barring south or we'd be in the sea! lol), we'd be on an unbundled exchange
Thank you all for your help and suggestions so far, apologies for wasting time by being a pillock!
Edited by deleted (Sat 08-Jan-11 21:53:08)