How to Control a GSM board using Arduino.This video explains how to make a call & how to send SMS from an Arduino through GSM
Many are confused with the connection.Generally Rx goes to Tx & Tx goes to Rx..This is the rule.But the GSM board I',ve used here has a MAX232 IC & T1IN/R1OUT of 232 IC is printed as TX/RX & not that of GSM SIM300.
If this is not working for you simply swap the connections.The connections shown in video is correct when you use a NSK GSM board.
Always ensure that
Rx of Arduino (pin 0) goes to pin 11 (T1 IN) of MAX232 IC &
Tx of Arduino ( pin 1) goes to pin 12 (R1 OUT) of MAX232 IC.
No matter whether you've or not the 232 IC ,as we are using TTL logic signals www.alselectro.wordpress.com