... RS232, RS485 Standard and Band: GSM850/900/1800/1900MHz 3G modem. Designed with industrial grade, supports SMS, CSD, RS232, AT Commands ... , with the function of accessing internet by dial-up, etc. It ... function8. Standard AT command interface B. Hardware System1.Interface RS232 serial port, rates: 110~230400bits/s Indicator lights: "Power", "ACT", "Online" ...