[Sony Xperia XZ1 Compact Guides, News, & Discussion] nlra:
Yup; long time no post, but that was me; heh.

Technically the ROM is still 100% identical to SO-02K ROM. They just modify the contents of one partition ("oem"). Since the bootloaders on 99.9% of DoCoMo models are locked and not unlockable (unless you pay a third-party to unlock them for you...), and since the system and boot and vendor and bootloader partitions are all sigchecked, it is impossible for either an actual G8441 firmware or for a modified firmware/ROM to be flashed to it (unless you are @j4nn and have a super-secret bootloader exploit in your back pocket...)

This is actually happening not just with XZ1c, but many many many other Xperia models, and even other popular Android models by other manufacturers!! If you see a "new" or "refurbished" phone available in mass quantities coming from China on eBay, or on Aliexpress, then it's one of these "professional" outfits that take e-waste phones, harvest the working guts (motherboard and whatever else) from them, manufacture "new" casings for them (counterfeits of OEM casings), make a box that looks like the original, package the phone up in that box with counterfeit accessories (headphones, USB cable, AC/DC charging brick), shrinkwrap it, and sell as "new" (though some of the more reputable vendors might call it "refurbished").

These have flooded the market over the past 4-5 years, maybe longer.

Because the ROM (including the modem firmware) is still the SO-02K ROM. Nothing has actually changed with functionality. If you want the phone to report the correct model# again, all you have to do is re-flash the oem.sin from the matching SO-02K firmware to your phone. Voila.

None of them are new. The brand-new counterfeit casings/shells are dang impressive, though. If inspected closely, the flaws become obvious, but they are "good enough" that at a casual glance they can easily trick people into thinking they are the genuine article.

This is 100% true: the IMEI for SO-02K is a different range/prefix vs. the IMEI for actual G8441. However...most of these phones are being sold in bulk by distributors (like, the listing will say they have Qty: 10 or whatever...in reality, they have many more than that at their disposal, and they will just update the listing or re-list again after they "sell out" of their "10"). So there is no single IMEI for a given one of these listings.

So even if you can get the seller to tell you the "IMEI", there is no guarantee they are telling you the actual IMEI of the specific unit they will actually ship to you. I suspect that a lot of these sellers have a mixture of G8441 and SO-02K phones (probably they just harvest good motherboards from various retired XZ1c, and if it happens to be SO-02K, they modify the OEM partition in the aforementioned way since they know the G8441 model is more valuable and will fetch more $$ in a sale). So what you end up with could be luck of the draw in a lot of cases...even if someone else previously got an actual G8441 from a given seller, that is no guarantee you will be as lucky from the same seller. The SO-02K are being repackaged into a "new" outer shell that has "XPERIA" printed on the back like a G8441 does & does not mention "DOCOMO" like the original phone the motherboard was harvested from would.

I have found that when it comes to people (re)selling a single unit that maybe they originally bought from one of these counterfeiters, and they post actual pictures of theirs with the original box and such, the easiest way to instantly spot one of these fakes is if the box is the standard white Xperia rectangle box that the XZ1c originally shipped in, but the large gray "X" silhouette is super-dark and easily visible, whereas on a genuine box, the X silhouette is extremely faint and sometimes doesn't even show up in photography.

This is not accurate. First, compatibility with 3G bands in the U.S. is a moot point these days, since all of the carriers here have shut down their 3G networks and re-harvested the spectrum for LTE and 5G expansions. Second, the real problem is lack of LTE band 2 support on the SO-02K model, and LTE band 2 is widely used by all 3 nationwide mobile carriers here in the U.S.

You can get the SO-02K model to connect to U.S. carriers on other bands that they happen to be broadcasting on in your area. I have, and it works. But coverage is not going to be nearly as good as it would be with an actual G8441.

I have. It works great. I used it to back up the TA partition before I ponied up for the paid SIM and bootloader unlock.

If you are actually in the U.S., this claim is confusing to me, since I'm not sure why you would be surprised that you were unable to get 3G phone calls to work. There is no carrier left in the U.S. that I'm aware of that runs a 3G network anymore, so there is no way for you to complete a 3G phone call in the U.S., period. Not with an SO-02K, not with a G8441...not with any phone. It's dead, Jim.

I can't remember for sure but I think maybe T-Mobile is still running a limited *2G* network in certain areas. But that is also scheduled for shutdown, assuming it hasn't already happened.

I too have also noticed a recent phenomenon on eBay recently where some of these counterfeiters are getting lazy & using an older-style of Xperia packaging for all of the Sony phone models they sell, rather than generation-appropriate packaging. It's pretty sloppy, especially if you know what the original box for a given model SHOULD look like.

This is a bummer to hear, but thank you for reporting this! It means my theory about whether some of these counterfeiters figured out how to regenerate or restore lost DRM keys is officially debunked. You are the first report I have heard of receiving one of these phones from a Chinese seller and having the bootloader come already unlocked. But if they are just harvesting motherboards from recycled phones, it was bound to happen eventually!