a-gsm 2.064 hardware connectivity (use it with HARDWARE serial communication examples-a-gsm-examples_0.8.rar) a-gsm 2.064 Arduino Uno Arduino Mega2560 TXD(RX)-pin D3 TX-pin D1 TX1-pin 18 RXD(TX)-pin D2 RX-pin D0 RX1-pin 19 power(IN) -pin D7 pin D7 pin D7 status(OUT)-pin D5 pin D5 pin D5 resetM(IN) -pin D6 pin D6 pin D6 Other pins (Vin, 5V, GND, Arduino reset) are in Arduino standard. WARNING!!!! When use with Arduino Uno, please be careful at possible short-circuits between a-gsm 2.064 pins and Arduino Uno components and board! High power audio (more than 500mW RMS)! You can damage your years! Use it with care when headset is connected. We recomend to use AT+CLVL=25, audio setup command in order to limit the output power.