In this site we presented two localizer without GPS that uses only the GSM cell to determine the position.
The radio mobile network is made up of a number of adjacent radio cells, each of which is characterized by an identifier consisting of four data: a progressive number (Cell ID), a code related to the area in which that given cell is (LAC, or Local Area Code), the code of national network to which the cell belongs (MCC, an acronym for Mobile Country Code), and finally the company code (MNC, or Mobile Network Code), which obviously identifies the phone company itself. For this reason, once a cell name and coordinates are known, and considering the maximum distance allowed between this cell and a phone before the phone connects to a new cell, it is possible to find out, approximately, the most distant position of the phone itself. For example, if the maximum distance has been determined to be one mile, the cell phone can be within a one-mile radius. It can be deduced that the more cells are found in a given area, the more precisely one can determine where the phone is located (up to 200-350 feet).
To explain how the systems works, we made this page. You have to insert the data of the GSM cells and then the PHP page gives you the position and the range.
Not all data cells are necessary. The important one is the Main Cell. A lot of program for smartphone give you the Main Cell. Someone give you also the neighbour cells.
This program can shall the information in HEX format or Decimal format, the system convert the informationo automaticaly but you must chose the format.
To determine the coordinates we use Google Database and the maps shows also the range of approssimation.