Modem personalization for Multi-IMSI number

[Nikint]

Hello,

We are working on a project having nRF9160 and STM32 microcontroller. We are using Serial LTE Modem firmware application for nRF9160.

We want to personalize the modem to use a specific SIM card. For this, we found the AT command "%XUSIMLCK" to lock the modem for dedicated IMSI number.

Our approach is like, STM32 read the IMSI number and personalize it so if user changes the SIM card then that new SIM will not work.

Here are few queries related to modem personalization -

1. We want to use multi-IMSI numbered SIM card. So, can we use "%XUSIMLCK" command to lock the SIM card? If yes, then let us know the detailed approach for Multi-IMSI SIM card personalization.

2. Does IMSI number integrated in SIM card? Does it need cellular network to read the IMSI number?

3. Can we read all IMSI numbers from Multi-IMSI SIM card using "+CIMI" AT command?

Your quick response appreciated.

Thank you.

[JONATHAN LL]

Looking in to you questions will update:

3. Can we read all IMSI numbers from Multi-IMSI SIM card using "+CIMI" AT command?

Only the active profile will be shown\read. https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/access_uicc/cimi.html?cp=2_2_0_12_1 

AT+CIMI
284011234567890
OK

2. Does IMSI number integrated in SIM card? Does it need cellular network to read the IMSI number?

the IMSI is stored on the SIM, so does not need network connection. 


Regards,
Jonathan

[Nikint]

Just to add few more queries on similar front -

1. Can we personalize (Lock to use only dedicated SIM card) the modem to other identifiers like UCCID or any other identifiers for Multi-IMSI SIM cards?

[JONATHAN LL]

Hi,

There is some explanations in the AT command docs on the %XUSIMLCK,  did you not find this sufficient in answering you problems?

IF you want more detailed info I will forward the request to our cellular team. 

Regards,
Jonathan

[Nikint]

Hi,

It is not much clear from documentation. So it is great to forward this request to cellular team. Most probably we are looking for locking Multi-IMSI numbered SIM card to modem and how any other identifier from Multi-IMSI numbered SIM card can be used for locking.

Thank you.

[JONATHAN LL]

Update:

%XUSIMLCK implementation is done based on ETSI TS 122 022 https://www.etsi.org/deliver/etsi_ts/122000_122099/122022/13.00.00_60/ts_122022v130000p.pdf.  It is not possible to lock the device to ICCID or some other information than defined in AT reference guide.

In case of multi-IMSI SIM cards, all IMSI codes in the different profiles shall be added to lock data by AT%XUSIMLCK command. As per AT reference guide (Set command ) 24 IMSI codes can be given. 

“When <facility> is PS, <pers_data> can contain a maximum of 24 IMSIs as specified
in 3GPP TS 31.102 Ch. 4.2.2 EFIMSI. Fifteen IMSI digits can be given. The format is
the following: IMSI1:IMSI2:...:IMSIn” 


Regards,
Jonathan

[JONATHAN LL]

If there is no other inquiries then close this case. 

[Nikint]

Thank you Jonathan.

Closing this thread.