A method and system of updating location information of a portable computing device is disclosed. Location data is received from a positioning device. A voice link is utilized for communication between the portable computing device and a call center. A dual-tone multi-frequency signal is mapped to a pre-determined range of movement. The dual-tone multi-frequency signal is transmitted to the call center when a longitude measurement in the location data indicates a change in longitude that is within the pre-determined rage of movement. The dual-tone multi-frequency signal is transmitted as an indicator of longitude change of location of the portable computing device. In addition, the dual-tone multi-frequency signal is transmitted to the call center when a latitude measurement in the location data indicates a change in latitude that is within the pre-determined rage of movement. The dual-tone multi-frequency signal is transmitted as an indicator of latitude change of location of the portable computing device.