AT command reference for the SIM900 GSM/GPRS module, provided as a 1.53 MB PDF. The manual lists the commands used to control calls, SMS, network registration, GPRS data and module settings over the serial interface. Repair technicians and integrators use it to test a module with a terminal program, query signal quality and SIM status, and confirm that firmware responds correctly. Check the module firmware revision, as supported commands and responses can differ between releases of the SIM900 firmware.
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