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FPLMN

FPLMN Clearing & Modem Reset (AT Commands Guide)

FPLMN (Forbidden PLMN List)

This section explains how to:

  • Check the contents of the FPLMN list

  • Clear the FPLMN list when required

1. Check FPLMN Contents

To view the current forbidden network list stored on the SIM, use:

AT+CRSM=176,28539,0,0,12

Purpose: Retrieves the list of networks that the SIM is currently restricted from connecting to.

2. Clear FPLMN (Forbidden Network List)

To clear the FPLMN list, use:

AT+CRSM=214,28539,0,0,12,"FFFFFFFFFFFFFFFFFFFFFFFF"

Purpose: Removes all forbidden networks, allowing the device to attempt connection to previously blocked networks.

Modem Reset Using CFUN (Airplane Mode Toggle)

Turn OFF Airplane Mode (Disable RF / Reset Modem)

Turn ON Airplane Mode (Enable RF / Resume Operation)

Purpose: Resets the modem’s radio stack and forces a fresh initialization.

Follow this sequence for best results:

  1. Clear FPLMN

  2. Restart the device

  3. Reset the modem radio


Expected Outcome

  • The modem performs a fresh network scan

  • Previously blocked networks become available again

  • Improved chances of successful network registration


Best Practices

  • Use this procedure when devices are stuck on no service / limited connectivity

  • Especially useful after repeated failed network registration attempts

  • Allow a few seconds delay between AT+CFUN=0 and AT+CFUN=1 for stability

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