Abstract: The present invention relates to a telephone number inquiry method and a database for all residents. A main feature of the present invention is that a third name belonging to a second object is introduced in a first object of the database. The third name is for recording employer's name or superior company name which can therefore be inquired through the telephone number inquiry of a related third party other than the holder of the telephone (number) record. Furthermore, based on the third name of known employer's name or superior company name, a colleague of the third party or related company name can also be inquired. Various ways of accomplishing the objectives of telephone number inquiry for all residents are provided.