Hello friends, today's post as the name suggests is about how to send SMS with Arduino UNO and SIM900D using AT Commands. There are different types of SIM900D modules available in the market, so it doesn't matter which module you are using. All SIM900D modules work at AT commands basically so today I am going to show you how to send an SMS via AT commands without using any Arduino library. You should first read the AT commands manual which will give you an idea about AT commands. AT commands are special sets of commands which are used for communicating with SIM900 module. Using these AT comma ...