The tag 'aronno' is only used once. This is the project:
modem on off
Use an optocoupler to on or off SIM908 modem.
Turn on the optocoupler for few seconds to on and off the SIM908 modem.
Use an optocoupler to on or off SIM908 modem.
Turn on the optocoupler for few seconds to on and off the SIM908 modem.