If there's ever an emergency, and you've used your cell phone to call for help, the personnel taking your call can use a type of phone number finder system to find your address. For example, if you're at home and someone is sick, you may decide to call for emergency services. When your phone number appears on their screen, the emergency personnel can use a reverse system to find your location. Technically, this type of system is only available to emergency personnel. This is because cell phone numbers are protected by privacy laws. However, the public can get this information as well. You can perform a search on the Internet for a reverse phone directory. But, you would need to pay for the report.