IMEI update issue

RE: IMEI update issue

dejans — Tue, 07 Oct 2025 08:22:06 GMT

Hi,

Programming IMEI documentation specifies that "nRF9151 comes with a preprogrammed IMEI and allows for a one-time replacement of the factory IMEI."

Programming IMEI mentions "Each device must be programmed with a unique IMEI code. IMEI writing is one-time programmable and cannot be reversed after programming. The device can become unusable if the wrong IMEI is written."

Best regards,
Dejan

RE: IMEI update issue

Vahram — Mon, 06 Oct 2025 15:38:47 GMT

Hi Dejan,

I understand that the IMEI cannot be rewritten, but will it try to use the <factory default IMEI> if the other one doesn't work? Or can we configure it to do so?

It does somehow store the default IMEI in it, so I believe there is a way to use it even though there is another IMEI programmed

Thanks

RE: IMEI update issue

dejans — Mon, 06 Oct 2025 12:05:11 GMT

Hi,

Here is an update on writing IMEI once and then trying to change it.

It is not possible to recover/change IMEI.

Once an IMEI is written to the device, it cannot be changed or recovered. This is a permanent, one-time operation mandated by GSMA regulatory standards to ensure device identity cannot be altered after deployment.

This is highlighted in the AT Command Reference Guide with the following caution:

AT%IMEIWRITE

"CAUTION: The command is a one-time operation. When the modem has been activated or the %IMEIWRITE command has been given once, the command cannot be used anymore. The device can become unusable if the wrong IMEI is written."

AT+CFUN

"The set command disables features that are used in the nRF91x1 SiP and device production, such as RF calibrations. It also prevents updates to the IMEI using the PTI firmware and the %IMEIWRITE command."

Due to this industry-wide requirement, there is no recovery mechanism available.

Best regards,
Dejan

RE: IMEI update issue

dejans — Mon, 06 Oct 2025 09:37:20 GMT

Hi,

Evluma Did you manage to resolve the issue? Can you provide an update?

[quote user="Evluma"]I am not sure why it is returning "000000000000000", while the documentation states it will return the stored IMEI regardless of success or failure of an IMEI update via %IMEIWRITE.[/quote]

Did you get all zeros as output from imei-read? Can you show the result?

[quote user="Vahram"]The chip doesn't seem to have any safety mechanism to prevent this from happening, so I think that's what we have.
I hope there is a method to force the board to use its default IMEI so that it can still connect to LTE. Still, I haven't found anything like that yet.[/quote]

Vahram Has your issue been resolved? Has your device been able to connect to LTE network? Can you provide an update on current status?

Best regards,
Dejan

RE: IMEI update issue

Vahram — Sat, 04 Oct 2025 20:56:15 GMT

Hey there!

I'm not sure if you're still experiencing this issue, but on my nRF9151 board, I had the same behavior. It appears that the first time we wrote 0x0 as an IMEI address. Note that the 0x0 can come up because of doing something like 'atoi("non-imei-string")'.

With 'nrfutil 91 imei-read' command it returned following:

```
slot 0: <factory default> slot 1: 000000000000000 ```

The chip doesn't seem to have any safety mechanism to prevent this from happening, so I think that's what we have.
I hope there is a method to force the board to use its default IMEI so that it can still connect to LTE. Still, I haven't found anything like that yet.

Hope this helps somebody :)

Best,
Vahram

RE: IMEI update issue

dejans — Wed, 14 May 2025 09:50:00 GMT

Hi Warren,

Which IMEI is read with imei-read?

Best regards,
Dejan

RE: IMEI update issue

Evluma — Mon, 12 May 2025 18:13:35 GMT

[quote userid="100458" url="~/f/nordic-q-a/121325/imei-update-issue"]it is returning "000000000000000" instead of "359404230716624"(factory default) or "358757450008449"(desired IMEI)[/quote]

The "359404230716624" is the default loaded IMEI and I tried to write the IMEI "358757450008449". This is not a case of multiple writes of an IMEI.

I am not sure why it is returning "000000000000000", while the documentation states it will return the stored IMEI regardless of success or failure of an IMEI update via %IMEIWRITE.

Cheers

Warren

RE: IMEI update issue

dejans — Fri, 09 May 2025 12:32:42 GMT

Hi,

How many times have you tried to write IMEI?
nRF91x1 production test AT command guide specifies that nRF9151 LACA A0 module includes a default
IMEI that can be changed once.

Please find below a caution note.
CAUTION: The command is a one-time operation. When the modem has been activated or the
%IMEIWRITE command has been given once, the command cannot be used anymore. The device
can become unusable if the wrong IMEI is written.

Best regards,
Dejan