Welcome to our Community Forum and sorry to hear about the strange dial tone on your landline. Can I ask whether your phone is plugged into a wall socket or is it into the back of the Hub? If it's via a wall socket, can you plug your phone into a different wall socket or try a different phone to see if it behaves like that?
Can i ask whether it was sudden or has it happened like that after a change (such as a fault, feature added/removed) and can you try and describe the strange noise?
I'm sorry for the questions but I'm trying to get a better understanding so I can help.