SIM800L: SIM not inserted

Summary

I have connected the SIM800L module to an Arduino board and I am able to communicate with it through Serial. The module responds correctly to all commands but seems to have issues detecting SIM cards.

Example:

SEND: ATI
ATI
SIM800 R13.08

OK

SEND: AT+CMEE=2
AT+CMEE=2
OK

SEND: AT+CPIN?
AT+CPIN?
+CME ERROR: SIM not inserted

Details

Power supply

  • Voltage: 4.1V
  • Max amperage: 2A

Module connections

  • VCC to power supply
  • GND to power supply
  • GND to Arduino board
  • Rx/Tx to Arduino board

In this case I am using a Heltec LoRa 32 V2 which uses 3.3v for GPIO.

Potential solutions that didn’t work

  • Re-solder SIM card holder pins
  • Different SIM cards (all 2G compatible)
  • Different SIM800L modules (tried 2)

If there’s any more information I can provide that may help find a solution please notify me.

Thank you.