... a telephone call center.12, AC power, phone short message to the user.13, when the ... host with the second frequency, quad-band GSM / GPRS wireless industry module, stable and reliable.15, the ... to ensure that power to work.16, all wireless systems, especially for garage, warehouse and other areas ... 20mA2, supply voltage: 9V-12V3, Working temperature: -10 °C - +55 °C4, supports quad-band mode GSM850/900 ...