Trouble with Phone

Question

Right. We moved from Orange thank god to BT less then a month ago, received home hub and phone. I set it up, everything worked great, 8mb phone worked ok.
About a week ago, our hub/phone were messing up. If we ever accepted a call and put the phone down all the hubs lights would start flashing. As well as picking up the phone to dial a number. There was dial tone but the hub would then i think restart.
Now, our original phone number doesnt work properly. At first it wouldnt work at all, people would try to ring but got nothing. Then people could ring and we heard it ring, but when we answered it nothing happened, it stopped ringing but couldnt here anything so would have to put the phone down.
So I got someone to ring the BT Broadband phone number, but it wouldnt work.
However now the BT Broadband Phone thingy mobob does work. We can receive calls and make calls fine, but not using our original number.
Also since the problems the internet speed peaks at 1mb (any time of day) and when our original phone number worked there was a TON of line noise. 
Now i have done everything, restarted the hub, reset the settings, change the filter, plugged another phone in and out of everything, phone line, filter, hub. The extra phone gets no dial tone where ever its plugged but the broadband calls work fine.
I rang up the tech guys and they think its a problem with the hub so are sending a new one tomorrow, but i doubt this will fix the problem.
I cant do a line check as we have no way of connecting to another network as you cant be using it. what can i do?

Answer 1

They are called copper "pairs" because of the two cables inside, the A leg and the B leg. The A is the earth and the B is the battery. You need both working for voice as that is how things have been since year dot but BB only uses one of the two, (not sure which but probably the B thinking about it!).  Google some geeky sites like http://www.vintage-radio.net/forum/showthread.php?t=28143 goes way over my head!!!