I wanted to know if my GSM sim800 is working or not. A mishap occured while I was experimenting around with my GSM module and I arduino uno. The link to the module which I bought: http://www.ebay.in/itm/SIM800-Quad-Band-GSM-Module-with-SMA-Antenna-Better-than-SIM900A-or-SIM900-/301782413058?hash=item4643a22f02:g:8LsAAOSwwbdWMidW I want to know ow can I check if my module is fine?

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    Plug it in to something and try using it. How do you tell if your car is working? You try using it. You don't just stand next to it and say "Oi, car, are you working?"
    – Majenko
    Feb 1, 2016 at 15:31
  • Can I check its working without an Arduino? Because the last one I had is now dead.
    – HDatta
    Feb 1, 2016 at 15:39
  • I do not know, since I do not know WHAT you DO have. The GSM has a PC interface, so if your PC has a 9 pin serial port, or you have a 9-pin USB adapter (how am I supposed to know that kind of thing?) then yes, you can. If not, then no.
    – Majenko
    Feb 1, 2016 at 15:40
  • @Majenko It would be nice though if your car could do that ;-)
    – Keith M
    Feb 1, 2016 at 21:36
  • It works ON and OFF. Suddenly it works. I tried with others too they work. It does not respond to AT commands. How can we try AT commands to check. Aug 6, 2018 at 8:27

1 Answer 1


Power it up and check the 'status' light. If it blinks with a 1 blink per second cycle, it is attempting to connect to the network. If it connects, it does a slow blink at 1 blink/3s, it made the network connection.

I don't know if your board does an auto-power-on, but you might need to push the power button or reset button.

  • Status light is ON as soon as the SIM900 starts. It do not blink and remains ON all the time. It is the Net light which then blinks and try to get the network.!
    – S Andrew
    Dec 6, 2016 at 11:28

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