This video describes how to connect a GSM SIM300 module with Arduino & make a call or send SMS. br The AT commands are sent from Arduino to GSM to achieve this.Sample sketch of making a call & sending SMS is explained. br Generally the thumb rule of connection is TX to Tx & Rx to Rx between Arduino & GSM.The GSM board used here for demo has RS232 circuit on board & the TxRx of MAX232 IC is printed & not that of GSM. br This is the reason for connecting straight between the boards.Remember the thumb rule of connection is always Tx to Rx & Rx to Tx. br br br br www.alselectro.