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Enable NB-IOT and LTE-M at the same time

Dear All,

I am building an application that needs to use NB-IOT and if that is not available then use LTE-M.

I tried sending this AT Command:


But this returns an error.

What I noticed is that if I enable both NB and LTE-M this command returns ERROR.

So I would like to ask if there is any way to achieve the following behaviour:

Check for NB-IOT network and if there is no connection to such network turn to LTE-M

Thank you all.

  • Hi.

    At the moment, only one LTE mode is supported at the time. See this note from the AT command documentation:

    Note: Only one supported LTE mode allowed at a time. This command is allowed only before activating the modem using the CFUN=1 command. If the mode needs to be changed, the modem must first be set to flight mode using the CFUN=4 command.

    However, the lte_lc driver will by default switch mode if it is not able to establish a connection. You can control this behavior with the CONFIG_LTE_NETWORK_USE_FALLBACK and LTE_NETWORK_TIMEOUT configuration options.

    Best regards,


  • Hello Didrik :)

    I'm also considering using both the NB_IOT and LTE-M capabilities of the nRF9160 at the same time. It can be something like LTE-M active until I meet a wall the signal doesn't pass through for example, then switch to NB_IOT, or simply like the example above where I will use the option with available network . Does the NRF9160 support both modes at the same time?  



  • Hi .

    Not much has happened on this front since my last reply, so the nRF91 still only supports one mode at a time.

    You can of course still disconnect from the network (AT+CFUN=4), change system mode (AT%XSYSTEMMODE=...), and then try to connect to the network again (AT+CFUN=1).

    But, the lte_lc library will still use the other mode as a fallback if enabled. Note that the lte_lc library only controls the initial connect, it will not monitor the connection afterward in case of loss of service.

    Best regards,


  • Hi Leonard,

    I also want to use the two networks at the same time when NB-IoT is not available, converts to LTE-M.

    have you found a solution or not ?

    Best regards


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