nRF9151 Connect Kit Unable to Register on Network Using iBasis SIM

[SatheeshRamasamy]

I recently purchased the Maker Diary nRF9151 Connect Kit (LTE-M/NB-IoT, nRF9151 SiP) and I am using the iBasis SIM that came with the Nordic Thingy:91. The device is unable to register on any LTE-M/NB-IoT network using this SIM.

I tested the device in two different locations with the same result:

• New Avenue, Gilroy (California)

• Mission Boulevard, Santa Clara (California)

In both places there was no network registration. Signal strength is always shown as +CSQ: 99,99, PDP context does not activate, and %XMONITOR remains stuck in searching.

Do I need any special activation steps for the iBasis SIM? Is the SIM compatible with the nRF9151 Connect Kit? Are there carrier/region restrictions in the locations above? Is any additional configuration required compared to the Thingy:91?

AT commands used:

AT+CFUN=0 AT%XSYSTEMMODE=1,1,0,0 AT+CGDCONT=1,"IP","ibasis.iot" AT+CFUN=1

Observed:

+CSQ: 99,99
%XMONITOR: 2 (searching)

AT+COPS=?
+COPS: (1,"","","313100",7), (1,"","","310410",7), (1,"","","311480",9), (1,"","","310260",7), (1,"","","310260",9), (1,"","","311480",7)
AT+COPS?
+COPS: 1

The device is able to scan available PLMNs, but attach never completes. Kindly advise how to enable successful LTE-M/NB-IoT registration using the iBasis SIM on the nRF9151 Connect Kit.

Thanks.

[dejans]

Hi,

You are located in India, but connectivity testing has been done in United States? Can you confirm and elaborate on this?

According to iBasis network coverage list, there is LTE-M support in United States. You can read more about SIM card support in the documentation.

You could try to change your system mode to LTE-M-only using AT%XSYSTEMMODE=1,0,0,0.

IBasis SIMs can be administered by nRF Cloud portal. For more information, please have a look at this discussion.

Best regards,
Dejan

[SatheeshRamasamy]

Hi Dejan,

Yes, that’s correct — I’m located in India, but my client and the nRF9151 Connect Kit are based in the United States.

The testing was carried out remotely at the following locations:

• New Avenue, Gilroy, California

• Mission Boulevard, Santa Clara, California

Both locations produced the same result initially — the device did not register on the LTE-M/NB-IoT network.

We also tested using the LTE-M–only configuration (AT%XSYSTEMMODE=1,0,0,0) and observed the same behavior (+CSQ: 99,99, %XMONITOR: 2, no attach).

====================================================================================
After your suggestion, we activated the iBasis SIM through the nRF Cloud portal:
  https://app.nrfcloud.com/#/register

We then re-tested with your configuration. Below are the AT command responses from the session:

AT
OK

AT+CFUN=0
OK

AT+CGDCONT=1,"IP","ibasis.iot"
OK

AT%XSYSTEMMODE=1,0,0,0
OK

AT+CFUN=1
OK

AT+CEREG=2
OK

AT+CSQ
+CSQ: 99,99
OK

AT%XMONITOR
%XMONITOR: 5,"AT&T","AT&T","310410","AF06",7,12,"0A1FFD11",66,5110,37,21,"","11100000","11100000","01001001" OK

AT+CSQ
+CSQ: 99,99
OK

AT+CEREG?
+CEREG: 2,5,"AF06","0A1FFD11",7
OK

From the output, it seems the device is detecting AT&T (MCC 310 / MNC 410) and shows CEREG: 2,5, which might indicate LTE-M registration.
However, the signal strength still reads 99,99, and it’s unclear?

Could you please confirm:

• Does CEREG: 2,5 indicate a successful LTE-M attach with AT&T using the iBasis SIM?

• Are there any additional steps required to enable data connectivity or verify network registration on the nRF9151 Connect Kit?

Thank you for your continued guidance and support.

Best regards,
Satheesh Ramasamy

[Achim Kraus]

SatheeshRamasamy said:

AT+CSQ

SatheeshRamasamy said:

However, the signal strength still reads 99,99, and it’s unclear?

Good point to start reading the documentation (nrf91x1_cellular_at_commands_v1.3.pdf, page 30), that will bring the missing clarity.

SatheeshRamasamy said:

%XMONITOR: 5,"AT&T","AT&T","310410","AF06",7,12,"0A1FFD11",66,5110,37,21,"","11100000","11100000","01001001" OK

Here the 37 and 21 are the values, which according nrf91x1_cellular_at_commands_v1.3.pdf, page 159/160 results in:

rsrp: -104 dBm

snr: -4 dB

[Achim Kraus]

SatheeshRamasamy said:

Does CEREG: 2,5 indicate a successful LTE-M attach with AT&T using the iBasis SIM?

yes.

SatheeshRamasamy said:

%XMONITOR: 5,"AT&T","AT&T","310410","AF06",7,12,"0A1FFD11",66,5110,37,21,"","11100000","11100000","01001001" OK

Using cellmapper with "310410" as provider, select "4G LTE" as network and search for tower 0x0A1FFD shows a base-station near the San Martin airport (South Valley Freeway). I guess this is near by.

[dejans]

Hi,

For more information, you can try to subscribe to modem domain event notification using %MDMEV command and to network status registration +CEREG with the highest value of the command parameter (using AT+CEREG=5).

Best regards,
Dejan