With Suntech ST3940B you can config up to "200 circular virtual geofences" that helping to protect the mobile asset GPS tracking, when your mobile asset cross any "virtual geofence" the ST3940B tracker sends alerts to a predefined mobile phone. ST3940B allow setup the follows "SMS alerts" to prevent emergencies in your mobile asset: (low battery alert, jamming detection alert, virtual geofences alert), when Suntech GPS tracker detect any of these 3 events, generate the "SMS alerts" and you receive them in the mobile phone. Suntech ST3940B standalone GPS tracker allow 3 real-time tracking modes that you can used depending of your need: (sending text messages with commands via SMS, from Suntech online server, using an external tracking management platform "edit default IP/port in device config"). Suntech has designed ST3940B GPS tracker with (IP67 - waterproof) certification, thanks to the IP67 protection you can continue working in the mobile asset tracking in extreme weather conditions. The target market of Suntech ST3940B GPS tracker is the tracking of any mobile asset and it is also a great alternative for requirements of (sea / land ) GPS container tracking.