All phone sockets in house except main entry point have nothing in them.
I plug my filter in to main socket and connect modem and cannot get a permanent connection.
I unscrew the socket from the wall and plug the filter and modem directly in to the socket behind and connection works fine - only problem being I cannot then use my phone/sky !
BT engineer here for 2.5 hours yesterday and completely stumped. Tested all sockets, extensions etc and could find no problem. However after 2 hours, connection came back for a reason he could not explain. So he went away.
36 hours later - connection gone again unless I uunscrew main socket and plug directly in to line. Have tried switching everything off for half hour then switching on again but no luck.
I had a problem where sometimes the modem box refused to accept there was a socket on the other end of the cable, when I powered up my PC. sometimes this took 30min to clear itself and other times 30sec. There was nothing wrong with the phone lines. I had to phone the rip off rate line and the tech at the other end changed the settings in the bt modem configure software in the start menu. I hope this is of help
You sound as if you have a proper NTE5 master socket, so, remove the plate that exposes test socket, your extn wiring should be connected to this plate, if there are any wires connected to terminal 3 (the ringer)- remove them. Now providing you have a filter in all other points (most importantly the Sky connection) you should have improved your Signal to Noise Ratio. Just a thought also, do you have sky plus ? one of the supplied units can cause b/band interference.