Is my Sierra Wireless MC7750 locked in any way?

Legacy Legacy AirPrime modules
1

I am facing issue as descrived in MC7750 and `CME ERROR: SIM wrong` with various SIM cards thread. TL;DR of that thread is:

AT+CPIN?
+CME ERROR: SIM wrong

However with different SIM cards and same SIM cards tested on Huawei modems, the problem is ONLY with Sierra Wireless MC7750 modem.

I came to the conclusion that my modem is somehow locked and I came here to confirm this.

How I can check it? Are there any AT commands to get confirmation of this? Could there be any other reason my SIM cards (I even bought different providers, like T-Mobile Polska or Orange Polska) are giving the error of wrong SIM?

2

you can check with other SIM card with different operators

3

I did. Did you read my post?

4

not sure if it can read anything on AT+CCID and AT+CIMI

i think there is some hardware issue on the sim card slot

5

AT+CIMI replies with a number, below number is redacted. AT+CCID gives an error.

AT+CCID
ERROR

AT+CIMI
000000000000000
6

i think there is some hardware issue on the sim card slot

7

I have two modems like that, on two different hardware units and both have the same problem with different sim cards each from different provider.

One hardware unit:

AT!SPN?
!SPN: 2, "Orange"

Second hardware unit:

AT!SPN?
!SPN: 2, "T-Mobile.pl"
8

To be clear, both return on those different SIM cards:

AT+CPIN?
+CME ERROR: SIM wrong
9

do you have a OK MC7750 modem can read those SIM cards?

10

I took my spare Sierra Wireless MC7455 and installed on the same hardware and everything works. I just started pppd(8) session on MC7455 and I have working Internet.

I believe problem is with the modem. I would like to know is my modem locked somehow that I cannot use any SIM card, but maybe only Verizon’s. I don’t know where to find generic firmware for my MC7750 modem to test this theory.

11

I have also mini-PCIe to USB adapter which has its own SIM card slot and modem MC7750 is NOT working there either and returns also AT+CPIN? return SIM wrong. At this stage I’m out of ideas. I would like to test different firmware version, but the ones from https://source.sierrawireless.com/resources/airprime/software/mc7750-firmware-package-history/ I doubt will work. I am using firmware 3.5.10.13 at the moment, but I have low expectations from firmware 3.5.10.9.

12

are you using a Verizon SIM card? (I remember using other SIM card, it will return SIM wrong)
BTW, what is the return of AT!SELRAT?

13

No, I am not. I don’t live in US. I used SIM cards of the providers mentioned in other threads - Orange and T-Mobile.

14

You can see the firmware download page, the firmware is for verizon

https://source.sierrawireless.com/resources/airprime/software/mc7750-verizon-approved-fw-3,-d-,5,-d-,10,-d-,13/

15

Do you know location of a firmware for MC7750 which is for any service provider?

16

No, i don’t quite see such firmware

Btw, did you check if t-mobile poland and orange poland have available LTE band for Mc7750?