HPPLMN Scan Criteria

[ManuelIoT]

Hello,

I'm testing nrf9160 with 2 SIM-Cards in Austria.

I'm always using automatic connect mode and only NB-IoT.

On Both SIM Cards HPPLMN Scan is enabled: 

6F31 - EF_HPPLMN - (Higher Priority PLMN search period)
> AT+CRSM=176,28465,0,0,1
+CRSM: 144,0,"01"

SIM 1 - Global SIM from Deutsche Telekom
IMSI: 9014057100XXXXX

EHPLMN: 901-40  (Global SIM)

OPLMN:
262-01
232-03
214-07
222-01
208-01
204-16
228-01
286-01
234-30
310-260

SIM 1 automatically connects to 232-03 (Magenta Austria) at my location.

After ~2 Minutes and then every 2 Hours die UE starts an HPPLMN scan.

SIM 2 - Telefonica SIM

IMSI: 2620756000XXXXX

EHPLMN:
262-07,
262-03

OPLMN: 262-07

SIM 2 automatically connects to 232-05 (Drei Hutchison Austria) at my location.

With this SIM 2 the UE never starts an HHPLMN Scan.

My Questions are:

1. Why does the UE start an HPPLMN scan with SIM 1 even though it is connected to 232-03, which is also in the OPLMN list and the only one for 232?

2. Why doesn't the UE start any HPPLMN scans with SIM 2?

Thank you!

br

Manuel

[Didrik Rokhaug]

Hi,

Which modem FW version do you use?

Why does the UE start an HPPLMN scan with SIM 1 even though it is connected to 232-03, which is also in the OPLMN list and the only one for 232?

It is probably scanning for the EHPLMN, which is a global network. As the network is global, it can potentially be found anywhere.

SIM 2 on the other hand only prioritize German networks. As the device is not in Germany, those networks will not be found, and the modem will not search for them.

Note that the behavior for SIM 1 will change in the next modem FW release, as it will then only search for global networks with a higher priority if it already is connected to a global network.

Best regards,

Didrik

[Achim Kraus]

> As the network is global, it can potentially be found anywhere.

So after half a year, is someone at Nordic able to demonstrate that? Where did you found the 90140? Did check that with the Deutsche Telekom?

[Achim Kraus]

As you read in the answer, Nordic assumes, that the network 90140 "can potentially be found anywhere". In my experience, the modem will not find it at all. Not in Germany, Greece, Spain, United Kingdom, Austria, Australia, Poland, Ireland, Slovenia, nor Czechoslovakia. Nordic also didn't provide the 3GPP specification, which really defines that, nor any example, where you can actually find such a 9er network. If you ask your SIM card provider, you will get the information, that this global number is not used by networks. Therefore the energy your modem spends every two hours is in vain.

[Achim Kraus]

With mfw 1.3.5, the modem will not longer search for the 90140.

See mfw_nrf9160_1.3.5_release_notes.txt:

- Fix for higher priority PLMN search. Global PLMN IDs (start with digit 9) are no more
  automatically considered to be suitable for higher priority PLMN search and selection.