Libreria per SIM900 quale usare ? - Software - Arduino Forum
Ks0142 keyestudio SIM900 GSM/GPRS Module Shield - Keyestudio Wiki
Sim900/sim900A Mini Module With Arduino UNO The Arduino IDE includes a library for their GSM shield using the Quectel M10 GSM chip, and Surprise! it is almost identical to the Sim900A chip!