Microcontroller › Arduino › gsmsim900A interfacing with arduino › Hi SumanI think you are
January 7, 2017 at 8:52 am #14330
I think you are making a mistake while writing the command: SIM900.println("ATD + +12128675309;"), there is no need of "+" sign between ATD and number. Try this way:
SIM900.println("ATD+12128675309;") and wait for the "OK" response. This ensure that the commcand has been executed successfully.
This might help you