VISIONTEK GSM Modem 81GR is a wireless cellular connection for 2-way data communication with a wide variety of remote equipment and Utility applications. VISIONTEK GSM Modem is compliant to high-power, tri band (900/1800/1900MHz) GSM transceiver, ensuring reliable connectivity well beyond the range of conventional cellular phones. Standard Power source is of AC 90-310 Volts with customized surge protection option. Power supply can be customized to various *DC power sources like 12V, 24V, 48V.