Meitrack MT90V4 it is also a GPS tracker with microphone / speaker that allow two-way communications with the person that has the tracker or active the "spy listen-in" to listen surrounding of MT90V4 Standalone GPS. For increase the safety on the GPS personal tracking, the Meitrack MT90V4 Standalone GPS integrate a "SOS - Panic button"; when the person feels a danger, or a possible accident can click the "Panic button" and MT90V4 send a SOS emergency alert. The GPS personal tracking with the Meitrack MT90V4 Standalone GPS tracker you can make it sending SMS messages or from a Tracking Management Platform on where you can view all positions or events that generates your MT90V4 tracker the 24 hours a day. You can setup the following SMS alerts in your Meitrack MT90V4 Waterproof GPS tracker: (low battery alert, panic button alert, geo-fences alert), MT90V4 send the SMS alerts to a predefined mobile phone. With the Meitrack MT90V4 GPS Personal tracker you can preconfigure up to 8 polygonal geo-fences and when the MT90V4 tracker crossing a geofence you receive a SMS message in the mobile phone with the exact "Geo Location".