Originally Posted by
wotnot
Ummm....not really sure if this is achievable at the hardware level ... for all sorts of reasons ~ really depends on exactly what you mean by being non-destructive ...ie; simple solution = remove sim card holder from PCB ...hackier solution would be cut your own sim card blank from suitable piece of plastic, and glue this into the sim card holder with something nasty like CA (superglue)...simple hardware blocker =) I mean to say, with the advent of 5G and beyond, it's unlikely the old S5 will be viable as a 'real' mobilephone in the near future.
You'll have more scope with a software approach - this might be as simple as loading (in firmware) the incorrect baseband modem driver. Real hacky example I use here as a bluetooth music player...this is a lenovo A399 'global' version. I wanted to k nobble it's cellular function as well, so I ended up searching for a (CN) firmware image and reflashed the phone with that, (set language to English), and you can stick any sim in it you like and it won't connect because wrong baseband driver =) It still starts up/shuts down saying something in Chinese...<grin>.. and then displays zero bars of 3G/4G reception regardless of whether a sim is in it or not, or if you're in a strong signal area
With an S5 you've got a bit more scope, as you can replace the stock samsung bootloader and firmware image with something else ~ a custom recovery image flashed in, lineageOS or something -- I mean, android is just embedded linux more than not, and merely 'rooting' the phone (in the pure context of root), you can deny the -user- from accessing functions on the phone, prompting them for the root password, which you never divulge to the kids =) My previous phone was/is an Asus t00f flashed with cyanogenmod and if I wanted to turn baseband off altogether, I could by changing system config file used at startup, and of course password lock the recovery function so users can't access that either. (my 80yo mum has this phone now, and it still going good with the cyan ROM)
Iirc a lot of the samsungs can be loaded with different baseband .bin files, which actually results with 'broken' cellular connectivity ... which is what most folks *don't* want to happen to them, but in this case it's exactly what you want. Place to start looking for info and 'ROM' images etc et al blabla, would be XDA forum -->
I think if you had root, you could uninstall the related android.com files from the realtime image, so in effect there's no user interface to interact with the baseband at all (even though it's working), but any modification like this means you have to password lock the recovery image, to stop users using recovery mode (which effectively replaces all the files you removed from runtime)...ie; you'd remove dialer, phone, sms, a couple of other comms layer things -- these are all replaced when device is reset via recovery mode. If you had root and something like TWRP flashed in, you achieve full root privs and pretty much control of what goes on -- messaging/phone apps don't work 'coz you deleted necessary .com files - users can't get past that as they can't use recovery mode. Very likely there's copies of the original firmware images on samsung's site that you can download and reflash the device with to bring it back to original.
Normally speaking, the firmware image is spread across multiple partitions of the MMC ; one of these partitions has the device config files ...this was a number of years ago, and not specifically samsung, just my hackers view.....but you could for instance obtain a firmware image, unpack it into it's constituent parts, and mount those parts as filesystems...you can mount the entire OS image if you like ...but in this case, you're only interested in the sysconfig part, disable the cellular capabilities by editing those files, save, repack the firmware image and flash it to device. This way, it doesn't matter if user uses recovery mode, whatever you've turned off stays off, and the only way to change that is to reflash the device with a different firmware image.
The wifi antenna will be the cellular antenna at a guess, but if not you could disassemble the phone and disconnect/sever the cellular transceiver antenna and turn it into an NFC phone that only worked within 10metres of a tower =) I've no idea if this is the case however, it may used a shared antenna.
What you're specifically asking I think, is can the bandband IC be removed from a S5 without affecting any other functionality? I've no idea...it might not even boot for all I know...but that might be the case. I'm sure you can find someone willing to take your money to find out =) In any event, wouldn't be cheap and is hardware invasive. If you use the sysconfig files, (in linux speak), it just tells the kernel not to load that specific driver module and subsystems thereof, but who knows how much this breaks up at the OS level...ie; user tries to app to access telephony which tries to hook to non existent device interfaces, and it crashes and burns...stuff like that. Usually no, the apps just start, fail, and flag their defeat.
For sake of completeness - if you had you own android build/toolchain environment set up, the SDK of your choosing/need and an IDE, you could get the source-code of whatever you're going to use (or DIY), and leave out -all- the telecoms stuffs out, and pretend device is just a wifi tablet, and be done with it. Obviously if you're at this level, you wouldn't bother building the phone dialer or sms/mms mods etc related to cell usage.
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