... -GND power off Save powerBuilt-in RF module supervision Built-in RF module status detection Reset RF module when it out of serviceReset outlet ... models which can be selected.ProductModelNoteCDMA MODEMH6811USB Interface, Wavecom module inside, 800 Single band, 800/1900Mhz Dual band optional ... . H6821-Z+RS-232 Interface, ZTE module inside, 900/1800Mhz Dual band. Either +5VDC or + ...