Landline rings but after one ring goes to faxtone

Question

Hi. I have tried everything.My land line rings only once and then goes to fax tone. I can hear the faxtone as well as the caller.If I pick up the phone during that one ring, I can get the caller. If not, it goes to faxtone.I have never had a fax in my house or ever attached a fax to this number.Please help.