I bought a SIM900 GSM card to replace my previous 2G GSM card. but SIM900 seems not to be able to detect network even though Our cellular network support 900 & 1800 MHz. The card is powered up using a different power supply from Arduino.

Anyone can help? I conclude that network is not detected based on the blink of the LEDS.

Is there any other recommendation? Our ISP do not support 2G anymore. I just need to send SMS alert to cell phone in my project.

  • Using 2A supply? – Mitu Raj Dec 11 '17 at 16:47
  • Does the SIM have a PIN code? – toxicantidote Dec 12 '17 at 5:27

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