Hello friends! Today we will receive SMS messages with a SIM900 modem and an Arduino. In the earlier SMS sending tutorial , Arduino initiated a command and supplied message text. Receiving is different because a message can arrive at any time, including while the program is handling another modem response. Libraries SIM900 Simulation Libraries Latest library: SIM900A Library for Proteus V1.1 (October 2026) Other GSM modules: SIM800L · SIM800C · SIM808 Helping Tools Serial Monitor Advance : a serial terminal window for the UART of your board Serial Monitor Expert : the serial monitor with extra debugging tools LCD Library for Proteus V3.0 : 16x2, 20x4 and I2C LCDs to show your readings We will begin by checking the serial connection, configure text-mode notifications and inspect the sender ...