Welcome to the forums, and may I say that I'm really sorry to hear that your phone line is causing you some troubles at the moment, and I'd really like to help you out.
I've done some testing from this end, and can see no reason why you should be experiencing an issue with the phone line, there are no local issues, and the line itself doesn't seem to be experiencing any issues.
As you've confirmed that you've already tried another phone on the line, then the next step would be to book a technician to call out and investigate further for you, so I'll send you a private message in order to get things moving with this. Please look to the top left of this page where you'll see a red envelope icon, click on this and you'll see my message.
Just thought I'd check to see if you've been able to read the private message I sent to you on Monday, as I've had no reply.
Since my original post, the forums have gone through a little make over, so the red envelope icon has now moved and changed to a blue colour. You can find the envelope now on the top right hand side of this page, near your profile photo.
Should you wish for me to book an appointment for a technician visit, please let me know.