Open Reach will only support you up to the Master Socket.
The fact your broadband is working would suggest this isnt a BT fault, and your phone is connected to an extension socket.
If not already can you plug your phone into the master socket, and check this works (you get a dial tone), if this works you need to find out why your extension sockets have stopped working, it is often cheaper to phone up a local electrician or computer network engineer as they would be half the price of BT.
However if the fault still present on the master socket, BT should be able to attend and fix the issue free of charge.
Further to my response a few days ago, I wanted to follow up to check if you had any further questions regarding the answer provided.
I would appreciate if you could rate the service received to date.