Non-persistent FPLMN

[JonathanG]

I'm trying to set the Forbidden PLMN list on a SIM using an nRF9160 and it all works until I power the SIM off and on again, whereupon the list is empty.

Here's an example using the "at_client" example app on an nRF9160 DK with an O2 SIM inserted, and the nRF Connect Serial Terminal on the PC: 

> at+cfun=1
OK
> AT+CRSM=176,28539,0,0,12
+CRSM: 144,0,"FFFFFFFFFFFFFFFFFFFFFFFF"
OK
> AT+CRSM=214,28539,0,0,12,"32F40132F451FFFFFFFFFFFF"
+CRSM: 144,0,""
OK
> AT+CRSM=176,28539,0,0,12
+CRSM: 144,0,"32F40132F451FFFFFFFFFFFF"
OK
> at+cfun=0
OK
> at+cfun=1
OK
> AT+CRSM=176,28539,0,0,12
+CRSM: 144,0,"FFFFFFFFFFFFFFFFFFFFFFFF"
OK

What am I doing wrong?  I'd like the forbidden list to be remembered over a SIM power-cycle (which I'm sure it should).

Thanks for any assistance!

Jonathan

[Achim Kraus]

In my experience that depends on the used SIM-card.

[JonathanG]

I've tried three different SIM cards - Vodafone, O2 and 1nce.  They all behaved the same, each one in turn forgetting the FPLMN list over a power-cycle.

[Achim Kraus]

I'm just an other user. I did some tests about that list a couple of months ago and found that it depends on the SIM card. I don't have more details on it. 

[Alex Rawstorne]

Just some more info, customer says that when the modem is turned off (CFUN=0), and then turns on, the PLMN list is not persistent. This is not the case for the Onomondo SIM. They use 02, 1nce and Vodafone SIMS. After connection the SIM appears to power down and again the PLMN list is lost. What is the preferred method or retaining a persistent PLMN list which is SIM agnostic? Is there some unsolicited message they can use to reissue a refresh of the PLMN ?

[Hakon]

The modem will return to the same network after exiting PSM, if possible.

JonathanG said:

Do I need to be concerned about roaming after the FPLMN has disappeared?

I would check the PLMN ID with %xmonitor after every +CEREG notification, if the concern is accidentally entering into a roaming network.

[JonathanG]

Thanks Hakon.  I agree and so that's my next plan.

I'll check the PLMN after connection with AT%XMONITOR against our list of forbidden PLMNs and if it matches, disconnect, update the FPLMN list on the SIM and connect again.

[Hakon]

Alex Rawstorne said:

What is the preferred method or retaining a persistent PLMN list which is SIM agnostic?

I'm not sure there is a good way for this. When the modem wakes up from PSM it should try to connect to the same network, so then you shouldn't need to worry about connecting to some other undesired network. But if you want to keep the FPLMN list in the modem at all times regardless of SIM then rewriting it to the modem seems like the best solution.