Are you looking for an old friend but only have their name?
Their are alot of services online that will help you to locate your friends phone number. phone mnumber reverse look-up is a service offered by several sites and can be done for a small fee. Some sites offer this service along with a comprehensive look up of an address associated with that phone number.
If your a private investigator you may find that reversephoneid.com is a viable choice for your reverse lookup needs.
People do reverse lookups (address to phone number) for various reasons including trying to return a purse left in a restaurant where by only an address was discovered to trying to discover where a missing child who only remembers his or her address.