I have a question regarding librem phone. Since its running Linux and since I would imagine I have root access, I was wondering if its possible to spoof IMEI number as it may be banned in Australia, a lot of phones including OnePlus 7 was banned due to VoLTE Australian support requirements.
Since wifi mac address spoofing is possible as afaik the operating system reports the mac address of the wifi adapter to the modem, wouldn’t it be the same with IMEI spoofing?
The problem is that this functionality likely resides in the modem (if the functionality even exists) and we don’t have any access to the modem.
For sure this is necessary functionality in many countries.
This isn’t legal advice but in Australia it may or may not be legal to spoof your IMEI. However, until someone finds a way of doing that with the BM818 modem, it’s an academic question anyway.
How come we can easily spoof wifi mac addresses but not IMEI numbers? If the OS reports back the MAC address of your wifi adapter then wouldn’t it be the same thing with IMEI numbers?
I don’t really care cause over here they keep banning devices and I should have the freedom to use whatever device I want.
I don’t really have a good answer for that.
However, in respect of spoofing MAC addresses:
I’m not sure that there is a solid reason for the IMEI to exist at all (since your actual right to use the mobile network, and the terms and conditions pertaining thereto, stem from your IMSI, which is associated with the SIM, not the phone itself).
So, in summary, both the WiFi card and the modem card are blackboxes - but the WiFi card provides an interface to override the card’s MAC address while the modem card does not (as far as I know) provide an interface to override the card’s IMEI.
Cellular modem is in fact a separate computer with its own proprietary OS on board. All complications stem from that fact. Purism separated all of that nonsense into a separate detachable board and limited its means of communication with rest of the phone as much as possible. This is the best could be done in these regards as of today.
While this is pretty much true, I don’t know whether that is “the best [that] could be done in these regards today”. For example, one can change the IMEI for the pinephone because the Quectel EG25-G is not as locked down as the modem(s) on the Librem 5. Instructions to change the IMEI . It should be noted that changing the IMEI violates implicit agreements with Quectel and your use of their firmware, not to mention that it is illegal in many countries.
And, to be clear, the cellular network provider does monitor the number of changes in IMEI with a given phone number and, so, if you were to change your IMEI daily while keeping the same sim card (and associated phone number), they will know.
To be clear, in respect of the OP, only one change of IMEI is needed.
If one were attempting IMEI randomisation then yes.
I think that the EG25-G may not be compatible with the Librem 5 (low confidence either way on this claim as not tested). However if it were compatible then Purism doesn’t stop you from removing the BM818 and inserting an EG25-G.
PS
It looks likely that that command is model-specific (range-specific) and hence won’t work on the BM818.
Changing the IMEI by changing the module itself may be quite different from a legal standpoint. So that’s an extra dimension to that question.
I could have a batch of 100 BM818 modules and rotate them through each day and that may not fall foul of the law. However, for sure the antenna connector will either wear out or break or both. 
I don’t know about the laws but I do know that if you do this with a Librem 5 at some point after 3 or 4 the cell providers start trolling you and not providing as good of service.
This may or may not be useful for changing the IMEI:
Perhaps if someone has or gets a completely broken phone that’s going to the landfill but it’s still supported by one or more carriers, they can use that device’s IMEI on the Librem 5, and then dispose of the old device?
I have no idea whether that would be a good idea, legal, or within the carrier terms of service…
There’s also these I stumbled upon:
This person is apparently on the Fediverse here:
… including a) does it work at all on the modem side in a Librem 5 and b) does it cause other unrelated problems either on the phone side or on the carrier side.
It seems that the modem OS hacker biktorgi has dropped out of the pine and pure project’s hardware around late last winter.
Strangely, that project comments
The BM818 wipes its EFS when you update the firmware, setting your IMEI to 0000000.
(which seems like a bit of a weird design)
Anecdotally, there are some Librem 5 customers who have already updated their modem firmware (directions here: Reflashing modem firmware - Purism user documentation), so Purism must know all this already. Possibly though the backup and restore discussed there is more comprehensive than just the IMEI and the SN.
And just for fun … what would happen if you left the IMEI as zeroes i.e. chose not to restore it? For a mobile network provider doing blacklisting, maybe it would get through if the coding is slack but probably not. For a mobile network provider doing whitelisting, it is even more unlikely to get through.
Isn’t there post on here about someone that had a IMEI # that was all zeroes?
I have been looking and looking but I cannot find it.
I found one really really old reference (before the phone even existed). Hard to say (hard to do a search) when I don’t know what pieces of information you are remembering.
Given the apparent behaviour of wiping out the IMEI when the firmware is upgraded, it is certainly plausible that someone ended up with an IMEI of zeroes i.e. if that process experienced an interruption or a glitch.
In the US I had a y2k era Motorola T280 and got my hands on the maintenance software. I saved and then zeroed the IMEI and it worked well for years on AT&T hybrid no-KYC prepaid-monthly plan. I paid $1/Mb for data but I was able to serial cable tether. What a great phone for the time when WAP was still a thing.