Phone rings but can't make or answer calls

[#1]

My line has developed a problem whereby I am unable to make or answer calls, even though the phone rings when someone tries to call me. I first became aware of this a week or so ago.
When attempting to make a call there is no dial tone. When attempting to answer an incoming call, I can hear a ringing noise on the line through the handset, but the call does not connect. I have tried two different phones (one of them corded) and tried plugging the phone into the test socket behind the BT faceplate, but the problem remains. The ADSL seems to be unaffected.
Please would you be able to look into this for me? Thanks in advance.

[#2]

Our tests have found a fault at the exchange so I've raised that for you.
Should be fixed by Friday.

[#3]

Great, thanks for the quick response!

[#4]

Do you have any updates on this? I haven't heard anything since Tuesday, and it's now been 10 days since I first reported it.

[#5]

Sorry to hear it's still ongoing.
I've passed it back to our suppliers.

[#6]

We've got a dial tone now so I think it's fixed - thanks for your help.