Industrial Tri-Band 3G WCDMA Modem with GPS function. The GTM-201 series are industrial Quad-band GSM/GPRS modems with RS-232 and USB interfaces that work on frequencies of GSM 850 MHz, EGSM 900 MHz, DCS 1800 MHz and PCS 1900 MHz. The modems utilize the GSM/GPRS network for convenient and inexpensive data transfer from remote instruments, meters, computers or control systems in either live or packet data. GTM-201 series have the integrated TCP/IP stack so that even simple controllers with serial communications ports can be connected to the modem without the need for special driver implementation. With GTM-201, systems can be SMS and GPRS connection applications with various PLC and PC's. With the voice interface, these modems can also be applied to alarm systems with sounds.