AUTO-SIM stops working for T-mobile SIM

IoT Modules MC/EM Series
1

Hi,

I have EM7565 cellmodems and by default I have enabled AUTO-SIM (SIM based automatic Image switching) feature for them so that the carrier PRIs and associated fw images are automatically selected by the SIM that is activated.

I know SIM cards will specify MNC / MCC codes and if the preferred PRI differs from the active one, the EM7565 will change carrier PRI (and FW if needed) and reboot when switching SIMs.

This works well for ATT and Verizon SIMs, but not for T-mobile SIMs.

On one of EM7565 modules I have, its FW/PRIs are as following:

# /etc/scripts/modem-cmd  'AT!IMAGE?'
response: 'TYPE SLOT STATUS LRU FAILURES UNIQUE_ID   BUILD_ID
FW   1    GOOD   18  0 0      ?_?         01.08.04.00_?
FW   2    GOOD   3   0 0      ?_?         01.07.02.00_?
FW   3    GOOD   19  0 0      ?_?         01.14.02.00_?
FW   4    EMPTY  0   0 0                  
Max FW images: 4
Active FW image is at slot 3

TYPE SLOT STATUS LRU FAILURES UNIQUE_ID   BUILD_ID
PRI  FF   GOOD   0   0 0      002.008_005 01.07.02.00_ATT
PRI  FF   GOOD   0   0 0      002.012_001 01.08.04.00_GENERIC
PRI  FF   GOOD   0   0 0      002.001_000 01.08.04.00_SIERRA
PRI  FF   GOOD   0   0 0      002.003_000 01.14.02.00_TMO
PRI  FF   GOOD   0   0 0      002.015_002 01.08.04.00_VERIZON
Max PRI images: 50'
#

Specifically, the T-mobile specific FW/PRI are from the Release 15, whereas other FW/PRIs are from older releases.

Anyway, with AUTO-SIM enabled with T-mobile SIM card, data connection can be established and work well, however, from AT!IMPREF? command I can see that it is the GENERIC FW/PRI that has been activated, instead of the TMO ones:

# /etc/scripts/modem-cmd 'AT!IMPREF?'
response: '!IMPREF:
 preferred fw version:    00.00.00.00
 preferred carrier name:  AUTO-SIM
 preferred config name:   AUTO-SIM_000.000_000
 current fw version:      01.08.04.00
 current carrier name:    GENERIC
 current config name:     GENERIC_002.012_001'
#

Only if I explicitly specify AT!IMPREF=“TMO” command, could it swith over to the T-mobile FW/PRI:

# etc/scripts/modem-cmd 'AT!IMPREF?'
response: '!IMPREF:
 preferred fw version:    01.14.02.00
 preferred carrier name:  TMO
 preferred config name:   TMO_002.003_000
 preferred subpri index:  000
 current fw version:      01.14.02.00
 current carrier name:    TMO
 current config name:     TMO_002.003_000
 current subpri index:    000'
#

Lastly, the MNC / MCC codes read from T-mobile SIM are for T-mobile (310 260):

# mmcli -i 2 
SIM '/org/freedesktop/ModemManager1/SIM/2'
  -------------------------
  Properties |          imsi : 'xxxxxxxxxxxxxxxxx'
             |            id : 'yyyyyyyyyyyyyyyyyyyyyyy'
             |   operator id : '310260'
             | operator name : 'T-Mobile'
#

So, why didn’t AUTO-SIM switch over to T-mobile FW/PRI with T-mobile SIM card by default? how to further diagnose?

Many thanks in advance!

Harry

2

Hi @qingtao.cao.au,

Thanks for your question.

Technically, the AUTO-SIM (SIM based automatic Image switching) feature works according to the ICCID of using SIM. If the ICCD of using SIM is matched with the T-mobile FW table, device will switch to use T-Mobile FW.

So, could you please help to provide the ICCID of T-mobile SIM (AT+ICCID) in the your above issue? so that, I can check whether the ICCID exist in the T-mobile table.

Thanks,

3

@Vianney

Many many thanks for your reply!

So do you mean that only the SIM ICCID instead of MCC / MNC codes are checked by cellmodem during AUTO-SIM process?

Anyway, the ICCID of the T-mobile SIM card I am using is:

# /etc/scripts/modem-cmd 'AT+ICCID'
response: 'ICCID: 8901260195704779580'
#

Also as for the T-mobile FW table,

  1. where is it stored? on cellmodem?
  2. who is maintaining it?
  3. how to ensure it contains a comprehensive list of all sold T-mobile SIM on markets? is it possible to do this at all?
  4. the AUTO-SIM feature works for my ATT and VzW SIMs. Does this mean the ATT and VzW also has their specific FW tables?

Sorry I don’t know anything about this T-mobile FW table before, the Sierra Wireless Image Switching M2M Developer’s Guide document doesn’t mention it much.

Thanks again!

Harry

4

Hi @qingtao.cao.au ,
Sierra was aware of the issue. We are going to provide the fix in further
So do you mean that only the SIM ICCID instead of MCC / MNC codes are checked by cellmodem during AUTO-SIM process?
[Answer] No, the switching FW accords to both ICCID and MNN/MNC

  1. where is it stored? on cellmodem?
    [Answer]: It is stored on the device FW
  2. who is maintaining it?
    [Answer]: SierraWireless - FW provider
  3. how to ensure it contains a comprehensive list of all sold T-mobile SIM on markets? is it possible to do this at all?
    [Answer]: This is deep inside the mechanism how AUTO-SIM feature working. I don’t have much relevant info
    As far as I know, we’re in progress of enhancing the AUTO-SIM feature
  4. the AUTO-SIM feature works for my ATT and VzW SIMs. Does this mean the ATT and VzW also has their specific FW tables?
    [Answer]: Yes, they do

Please feel free to share any concerns you have. Help us tick “Solution” if my response is helpful
Thanks

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