If you ever need to research a particular unknown number which have been calling you, it's actually pretty simple with Phone Number Hunter.  The website allows you to search a particular area code and it lists down the cities associated with the area code. Of course, your search will only yield you the city or town but doesn't actually give you a specific address. In order to get specific information, like other reverse phone look-up service, you need to pay to get a more detailed information.

But I guess it's better than other look up services which automatically redirects you to their payment page and doesn't even give you any information. Of course, you can always Google the information they have on their website but Google will probably show you their website in response to your search query.