Equipped with RS-232 and USB interfaces, Model GTM-203M-3GWA operates on Quad-band WCDMA 850/900/1,900/2,100 MHz and Quad-band GSM 850/900/1,800/1,900 MHz frequencies. Unit is capable of switching between 3G or GPRS signals to maintain continuous connection. With integrated TCP and UDP/IP stack, GTM-203M-3GWA can work with simple controllers that have serial communication ports, and with voice interface, modem can also be applied to alarm systems with sounds.