When simulated, you’ll see AT and then OK in the Virtual Terminal if the library works. The SIM800L Proteus library is a limited but useful teaching aid for AT command flow. For real GSM development, always test on physical hardware. If you must simulate, consider using a virtual COM port + script for better control.
In Arduino code:
#include <SoftwareSerial.h> SoftwareSerial sim800(2, 3); // RX, TX void setup() Serial.begin(9600); sim800.begin(9600); sim800.println("AT"); sim800l proteus library