Hi Kariyappa,Check these | Microcontroller › Arduino › Request regarding interface of SIM900A with Arduino UNO › Hi Kariyappa,Check these September 20, 2014 at 12:30 pm #12210 AJISH ALFREDParticipant Hi Kariyappa, Check these things; 1) The baudrarte should match 2) The voltage levels should match, means the Arduino Uno operates at 5V logic and hence the SIM900A module should be at 5V logic, otherwise use a 5Vto3.3V logic level converter in the serial communication lines.
