nRF9160 cannot register to Nb-IoT network

[Basilio]

Hello,
I' trying to use the Serial LTE Modem application on an Actinius Icarus board. I configured the nRF project for the correct target, enabled COAP support, set Nb-IoT as preferred configuration. I'm using a SIM card by Things Mobile in Italy. I give the following AT sequence
AT+CFUN=4

AT+CFUN=41

AT%XSYSTEMMODE=0,1,0,0

AT%XEPCO=0

AT+CFUN=1

When I query signal quality using AT+CESQ I get rsrq/rsrp values near to 30/60

14:28:42.066 -> +CESQ: 99,99,255,255,31,61

The SIM card is active and READY and I can read its ICCID, etc...

Here is the output of CEREG

14:16:48.516 -> +CEREG: 2,"B7FA","01587171",9,0,0,"11100000","11100000"
14:16:48.914 -> +CEREG: 2,"B7FA","01587171",9,0,13,"11100000","11100000"
14:16:49.312 -> +CEREG: 2,"FFFE","FFFFFFFF",9,0,13,"11100000","11100000"
14:17:10.090 -> +CEREG: 2,"8EE7","09EBB5F5",9,0,13,"11100000","11100000"
14:17:11.614 -> +CEREG: 4,"8EE7","09EBB5F5",9,0,15,"11100000","11100000"
14:17:11.846 -> +CEREG: 4,"FFFE","FFFFFFFF",9,0,15,"11100000","11100000"
14:17:14.232 -> +CEREG: 2,"B66E","063AB787",9,0,15,"11100000","11100000"
14:17:14.796 -> +CEREG: 4,"B66E","063AB787",9,0,15,"11100000","11100000"
14:17:15.160 -> +CEREG: 4,"FFFE","FFFFFFFF",9,0,15,"11100000","11100000"
14:17:15.458 -> +CEREG: 4,"B66E","063AB787",9,0,15,"11100000","11100000"

I cannot register to network. I thought it was a SIM card  profile problem, but when I insert it into a common smartphone, it correctly registers to network (roaming), and the operator can track it successfully.

Why can't I connect using the nRF9160 Icarus board?

Thank you in advance for your help,

kind regards,

b

[Albrecht Markus Schellenberger]

Hello Basilio,

reject cause 13 and 15 point towards that your SIM card does not support Nb-IoT.

Cause #13 – Roaming not allowed in this tracking area
This EMM cause is sent to an UE which requests service, or if the network initiates a detach
request, in a tracking area of a PLMN which by subscription offers roaming to that UE but not
in that tracking area.

Cause #15 – No suitable cells in tracking area
This EMM cause is sent to the UE if it requests service, or if the network initiates a detach 
request, in a tracking area where the UE, by subscription, is not allowed to operate, but when
it should find another allowed tracking area or location area in the same PLMN or an equivalent
PLMN.

When connecting with your smartphone LTE is used, which is probably what the SIM card is registered for.

Please check with your network operator!

Regards,

Markus