NRF9160 not connecting ESM/EMM errors

[9160-DEV]

Hello,

I have an NRF9160DK board and a custom board running the SLM application that are exhibiting similar behaviour.  Both boards work fine with the supplied iBasis SIM.  When I use some purchased SIMs from the operator Vodafone I cannot get past "searching" (CEREG: 2) - I've left it a couple of hours and no success.  The Vodafone SIMS worked when I last tried them a couple of months ago, the signal strength is currently good (-90dBm) and Vodafone report no issues on their NB-IoT network according to their coverage map.

The notification output from the SLM contains:

+CNEC_ESM: 29,0                         User authentication failed

+CNEC_EMM: 19                            ESM Failure

I have contacted my supplier who have asked to check the APN settings.  I don't think it is getting far enough through the network connection process for this to take affect though.  Isn't APN after network connection?

Does anyone have any advice or experience that may assist me resolving this via the suppliers support?

Thank you.

[Charlie]

Hi, 

Checked your modem trace, it shows EMM reject cause is 15 (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.

NOTE 3: Cause #15 and cause #12 differ in the fact that cause #12 does not trigger the UE to search for another allowed tracking area on the same PLMN.

Not sure if your area is covered by NB-IoT network.  You can further confirm with AT+COPS=?(manual PLMN search in that area to see what NB-IoT networks are available). Or double check with Vodafone about the coverage.

Best regards,

Charlie

[9160-DEV]

Thank you for looking at the trace.

I don't know if I'm reading it 100% correctly, but the EMM reject causes appear to change depending on the towers shown by +CEREG, eg EMM 15, 26, 29.  See below. 

+CEREG: 2,"2421","07C18A1F",9
+CNEC_ESM: 29,0
+CNEC_EMM: 19

+CEREG: 2,"2421","07C18A1F",9,0,19
+CNEC_EMM: 15

+CEREG: 2,"B951","00363015",9,0,15
+CNEC_EMM: 15

+CEREG: 2,"0390","07CA806E",7,0,15

+CEREG: 2,"241F","07B68F15",9
+CNEC_ESM: 26,0
+CNEC_EMM: 19

+CEREG: 2,"2421","07C18A1F",9
+CNEC_ESM: 29,0
+CNEC_EMM: 19

In the same trace I have "No Suitable Cells"(15) and "ESM Failure"(19), plus "User Authentication Failed"(29) and "Insufficient Resources" (26).

Is the user authentication error likely to be a low level SIM issue rather than AT+CGAUTH mistake?

Vodafone shows "Good" NB-IoT coverage using their coverage mapper tools online, and no tower issues in the area (even if there were, it seems to be changing between towers so would have thought that wouldn't be an issue?

The output of AT+COPS=? is

+COPS: (1,"","","23415",9),(1,"","","23430",9)

The first is Vodafone and the second one EE.  When I ran it again I've also seen a third operator O2.