Hi Walter,
I thought I may have gotten hold of the wrong end of the stick. Apologies if so.
My line was fitted 12 years ago for my Business by B.T. where I also suffered from the infamous DACS. The other master socket (non NTE) was fitted nearly 30 years ago.
The 2 master sockets are both indeed separate lines and numbers. Both are ours, or B.T.'s whichever way you look at it!
About 8 years ago; whilst I was browsing the web on dial up, I had the misfortune of being caught up in a thunderstorm which promptly took out my Modem. Other than the modem, no other problems were found. The modem took the brunt.
I mentioned this to the B.T. Engineer when this problem I've got now arose, as I thought I may have a duff NTE. He didn't want to know and didn't give me the benefit of the doubt.
The cable supplying my line is of a combination of coloured bands on coloured wires and not solid coloured, if that makes sense. That's why I likened it to CAT5, though I doubt it is.
Only 2 of the wires are used, leaving the others (forgot to count how many!) free. None are twisted, which I thought would have been more tidy for one, as well as also putting noise 180 degrees out of phase.
On the other line, I can swear I can hear hum. I have disconnected any mains products near there and has made no difference. Also, I believe there is a noise which sounds like: tick-ti-tick-tick. God I'm crap at describing things
I think the drop cable in the porch for my line is in a really bad position. It hasn't been fitted very tidily and is open to the elements as well as being pretty dangerous in case of tripping.
I'd have hoped as Openreach were charging £150+ for coming out, that they would have replaced my NTE, the non NTE5 as well as the wiring from the pole etc. and who knows, maybe fixed the fault in doing so.
A couple of years ago, my line went totally dead (no voice or data). After testing the basics of filters etc. I registered a fault with B.T. online.
The next day, the Engineer phoned up saying there was a fault at the exchange which he'd fixed, but I'd be without the Internet for up to 10 days. As to why, he didn't say.
I got in touch with Pipex and they weren't aware of any faults. It took over a fortnight for things to get back to normal. From what I gather, I think a lift and shift had been done.
Phill