Using AT commands to control the LTE

[newnow]

Hello everyone! :)

I have a problem with LTE connection.
It worked for a few months; however, since a few days ago, the nrf9151 refused to connect to LTE.
I tried with 2 different SIM cards - no success with either and also no SIM card activity is logged.
Both SIM cards work fine on my mobile phone, so they are not the cause of the problem.

I also tried connecting to LTE using AT commands - that also didn't work.
Do you have any idea what the problem could be?

Thanks!

[Kevin Kotinkar]

Hi, which SIM cards do you use?

It wonders me that they work fine with your mobile phone, since those use a different technology (not LTE-M / NB-IoT).
You need specific LPWAN SIM cards.

You also specifically disabled NB-IoT, is there reason for that?

Check the SIM card status with: AT+CPIN?

Best,
Kevin

[newnow]

Dear Kevin,

Thank you for the quick answer. I am using an Onomondo sim card that came together with the nrf board. I also tried a Conexa sim card, and it was also unsuccessful.

On the Onomondo website, I can track the activity of the sim card, and when it was inserted in my phone, it was active, but when it is in the nrf board, no activity is recognized.

Regarding disabling NB-IoT, I was following commands from dev academy (academy.nordicsemi.com/.../) for manually connecting to the LTE network.

AT+CPIN command gives me "ERROR".

[Kevin Kotinkar]

Hi,

it would be AT+CPIN? including the question mark to check on the SIM card status.
You also first need to turn on the modem (e.g. AT+CFUN=1 or solely for the UICC/SIM card inteface with AT+CFUN=41.)

Also, I recommend to enable both NB-IoT and LTE-M to increase possible coverage
(run this command before CFUN command).
AT%XSYSTEMODE=1,1,0,1

The DK SIM cards come with a limited amount of data (I believe it was 5-10 MB), hope this is not the issue.
You can register the Onomondo SIM card to get additional data.

You may also try to factory reset the modem using AT%XFACTORYRESET=0 and ensure that you run on the latest modem firmware (v2.0.2):

https://www.nordicsemi.com/Products/nRF9151/Download?lang=en#infotabs

Best,
Kevin

[Charlie]

Hi Jelena and Kevin,

Please consider another potential cause:

Unusual blocking of LTE-M and NB-IoT by certain carriers | Onomondo Help Center.

You may record a modem trace and share it with us for analysis to better understand what happens at the low-layer communication protocols.

Best regards,
Charlie