Industrial Quad-band 3G WCDMA Modem with GTM-203M-A Accessory. The GTM-203M-3GWA is an industrial Quad-band 3G WCDMA cellular modem with RS-232 and USB interfaces working on frequencies of Quad-band WCDMA 850/900/1900/2100 MHz, and Quad-band GSM 850/900/1800/1900 MHz. The GTM-203M-3GWA enables inter..