A position determination method in a mobile unit uses the telephone number of a wireline telephone and a reverse phone-book operation for determining the location of a mobile unit. In one embodiment, a method for determining the location of a mobile unit using a telephone number of a wireline telephone in the vicinity of the mobile unit includes receiving at a server the telephone number transmitted from the mobile unit using wireless communication through a data network, retrieving an address associated with the telephone number in the server, and retrieving a location of the mobile unit based on the address. The server may provide location-relevant information using the location information. The system and method of the present invention provides a low cost solution to position determination in wireless hand-held devices and can be used to supplement the conventional positioning systems.