Features:_x000D__x000D_Computer debugging USB--TTL. This module is powered by: 5V-26V, 5V 2A power supply is recommended. After plugging in the motherboard, the power supply must be able to supply 2A. The reason is that the GPRS Shield startup current and the maximum top current required to work up to 2A, but the USB port can not provide such a large current, so the external power supply equipment must be provided. The other power supply port leads to the 3.7--4.5V power supply for lithium battery power supply. The serial port is perfectly compatible. The TTL serial port is compatible with 3.3 and 5V microcontrollers. _x000D_Make sure your SIM card is not locked. _x000D_The best baud rate for GPRS Shield communication is 19200 BPS 8-n-1 (GPRS Shield automatically matches baud rate by default). _x000D_Quad-Band 850 / 900/ 1800 / 1900 MHz - would work on GSM networks in all countries across the world. _x000D_GPRS multi-slot class 10/8. _x000D_GPRS mobile station class B. _x000D_Compliant to GSM phase 2/2+. _x000D_Class 4 (2 W @ 850 / 900 MHz). _x000D_Class 1 (1 W @ 1800 / 1900MHz). _x000D_Control via AT commands - Standard Commands: GSM 07.07 & 07.05 | Enhanced Commands: SIMCOM AT Commands. _x000D_Short Message Service - so that you can send small amounts of data over the network (ASCII or raw hexadecimal). _x000D_Embedded TCP/UDP stack - allows you to upload data to a web server. _x000D_RTC supported. _x000D_Selectable serial port. _x000D_Speaker and Headphone jacks. _x000D_Low power consumption - 1.5mA(sleep mode). _x000D__x000D_Specification:_x000D_Power Supply:5~26V_x000D_Four Frequency Range:850/900/1800 / 1900 MHz_x000D_Working Temperature:-40~85_x000D__x000D_Package List:_x000D_1 x Module_x000D_1 x GSM Antenna_x000D__x000D_Note:_x000D_The product is provided as is without an insulating enclosure. Please observe ESD precautions specially in dry (low humidity) weather._x000D_The factory default setting for the GPRS Shield UART is 19200 bps 8-N-1. (Can be changed using AT commands)._x000D__x000D_Interface Introduction:_x000D_Power select - select the power supply for GPRS shield._x000D_Power jack - connected to external 4.8~5VDC power supply._x000D_Antenna interface - connected to external antenna._x000D_Serial port select - select either software serial port or hareware serial port to be connected to GPRS Shield._x000D_Hardware Serial - D0/D1._x000D_Software serial - D7/D8._x000D_Status LED - tell whether the power is on._x000D_Net light - tell the status about linking to the net. _x000D__x000D_UART of UART pins break. _x000D__x000D__x000D_Microphone - to answer the phone call._x000D_Speaker - to answer the phone call._x000D_GPIO,PWM and ADC of GPIO,PWM and ADC pins break._x000D_Power key - power up and down. 1Computer debugging USB--TTL can be. This module is powered by: 5V-26V, 5V 2A power supply is recommended. After plugging in the motherboard, the power supply must be able to supply 2A. The reason is that the GPRS Shield startup current and the maximum to 2The best baud rate for GPRS Shield communication is 19200 BPS 8-n-1 (GPRS Shield automatically matches baud rate by default). 3Quad-Band 850 / 900/ 1800 / 1900 MHz - would work on GSM networks in all countries across the world. 4Control via AT commands - Standard Commands: GSM 07.07 & 07.05 | Enhanced Commands: SIMCOM AT Commands. 5Short Message Service - so that you can send small amounts of data over the network (ASCII hexadecimal).