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)

AT+CFUN=0

Turn ON Airplane Mode (Enable RF / Resume Operation)

AT+CFUN=1

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

Recommended Steps for IoT Device Reboot / Network Recovery

Follow this sequence for best results:

1. Clear FPLMN

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

2. Restart the device

3. Reset the modem radio

   AT+CFUN=0
   AT+CFUN=1

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Expected Outcome

• The modem performs a fresh network scan

• Previously blocked networks become available again

• Improved chances of successful network registration

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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