In some countries you just can just call the phone company and ask. In Denmark you can just call 118, give the phone number and get the address back or use one

In some countries you just can just call the phone company and ask. In Denmark you can just call 118, give the phone number and get the address back or use one of the numerous websites that taps into to the same data. Here is the result of a query using a random Danish phone number https://www.krak.dk/97405354/personer https://www.krak.dk/97405354/personer