Detailed Introduce：
                   Tri-Band GSM/GPRS 900/1800/1900MHz or Quad-Band GSM.GPRS  850/900/1800/1900MHz
                  · GPRS multi-slot class 10/8
                  · GPRS mobile station class B
                   Compliant to GSM phase 2/2+
                  – Class 4 (2W @ 900MHz)
                  – Class 1 (1W @ 1800/1900MHz)
                   Dimensions: 40mm*33mm*2.85mm
                   Weight: 8g
                   Control via AT commands (GSM 07.07, 07.05 and SIMCom enhanced AT Commands)
                   SIM application toolkit
                   Supply voltage range 3.4V - 4.5V
                   Low power consumption
                   Normal operation temperature: -20 °C to +55 °C
                   Restricted operation temperature:  -30°C to -20 °C and +55 °C to +80 °C
                   Storage temperature:   -40 °C to +85 °C