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,

please see similar discussions on UK Vodafone NB-IoT network:

https://devzone.nordicsemi.com/support-private/support/281921#permalink=735252

https://devzone.nordicsemi.com/support-private/support/260734#permalink=619494

https://devzone.nordicsemi.com/support-private/support/246226#permalink=544395

Let me know which one or neither of them can solve your problem.

Best regards,

Charlie

[9160-DEV]

Hello,

Unfortunately none of those fixed the issue.  

[Achim Kraus]

According your trace

+CEREG: 2,"2421","07D4E21F",9,0,19  

the modem connects to base station 513250 using NB-IoT and gets rejected.

Cellmapper.net shows that Vodafone (PLMN 23415) base station in Gillingham.

For the other +CEREG cellmapper doesn't know the base stations.

Maybe that helps.

[9160-DEV]

Thank you for this resource.  The base stations it finds when I have run it again are all surprisingly far away (5-6 miles) minimum.

[Achim Kraus]

You're welcome.

"surprisingly far away (5-6 miles) minimum."

on the countryside that should still work. Otherwise you may try out testing closer to the towers ;-).

[9160-DEV]

No change unfortunately, just better RSRP/RSRQ.

Do all towers support NB-IoT for a given provider, or is it the case that the NRF9160 polls each tower it finds until one appears that supports it?  I've driven to four local 'big' towers and the same result at each.

[Achim Kraus]

> Do all towers support NB-IoT for a given provider

I guess, this is more a question for your provider.

> +CEREG: 2,"2421","07D4E21F",9,0,19  

the "9" indicates, that NB-IoT is used. The cell-id "07D4E21F" is split into tower and section (at least that works quite often like that). The tower part is "07D4E2" and the section "1F". cellmapper works with data feeded in by smart phones.So they usually don't list the NB-IoT section, but the towers.

You may also to a neighbor hood scan AT%NCELLMEAS to see, which cells are there. Unfortunately, cellmapper requires the PLMN and you need to check the candidates + tower id to see, if their tower is somehow near by.

Even if the SIMs has worked some months ago, I would check that with the SIM provider.

One pitfall maybe, that it used LTE (instead of LTE-M) and connects to "old towers". But once the towers are updated, then they detect it's LTE-M and reject the device, if it's SIm has only a LTE subscription. I would also not set the APN explicitly and relay in the first step on the one selected by the SIM.

Just in the case you want to try an other firmware, you may check with my demo zephyr-coaps-client using the prebuild nrf9160dk_nrf9160_ns_full.hex  . Apply it with 

nrfjprog --program nrf9160dk_nrf9160_ns_full.hex --chiperase --verify -r

and see, if that connects.