Cell phone tracking can be defined as attaining the current position of a cell phone whether stationary or while moving. Tracking is possible in a restricted area either by multilateration of radio signals between radio towers and the cell phone or via GPS. While multilateration requires emission of roaming signal to contact next closest antenna tower without an active call, GS M is based on signal strength of closest antenna towers. Measurement of power levels and antenna patterns coupled with the concept that cell phone always communicates wirelessly with one of the nearest base stations forms the foundation for using technology in cell phone tracking. Use of multilateration for cell phone tracking is referred to as GSM localization.