... design, ensure modem alive GPRS link detection and redial (work with Hongdian dialup software) Support dial up control Send SMS via PC ... ProductModelNoteCDMA MODEMH6811USB Interface, Wavecom module inside, 800 Single band, 800/1900Mhz Dual band optional. H6821-Z+RS-232 Interface, ZTE module ... . H6821-WRS-232 Interface, Wavecom module inside, 800 Single band. Either +5VDC or +7.5~26VDC. H6821-W2RS-232 ...