I got a call telling me I owe almost $400.00 but t...

I got a call telling me I owe almost $400.00 but they say the cannot tell my who I owe the debt to. They gave me a medical license number that I cannot connect to anyone. I am not sure if this is a scam or not. I called my doctor and they have no record of this. I don't see why I should pay something they cannot tell me who it is from.