[Sprint Galaxy S 5 General] FNetV1:
For my Sprint Samsung Galaxy S5 (SM-G900P) there was an extra step that I needed to perform in order to unlock it for domestic usage according to: https://idoneapps.com/settings.php (Thanks [MENTION=1088268]eurohu[/MENTION]nder for pointing this out for me). According to this quoted info, I am supposed to click on GCS settings on their paid for version of IDONEAPPS, but dont worry, I know that on the free version there is no such fancy button labeled "GCF", but fear no more! I will show you how to access the same exact menu where that fancy "GCF" button on the paid-for version leads to, its none other than simply clicking on the IOTHIDDENMENU button that I can see on your screenshot as button #2 on the bottom list, there you will see a series of menu, I believe the one labeled"Testmode" or something like that from the big menu leads you exactly to the same spot (which is the "SERVICE MODE") as if you were to click on the "GCF" button fron the paid for version, there you can just continue to follow the instructions on that page as it will be exact, depending on many factor and firmware version you are running.

Now that you have access the SERVICE MODE (or in other words "GCF"'s target destination if you were using the paid-for version) You would go to [2] UE Settings & Info, then [1] Settings, then [1] Protocol, then [4] GCF (note: MAYBE the "GCF" button on the paid for version leads you directly to this spot, bypassing the other menu options directly, maybe yes, maybe no, but it doesn't matter, the point is that you made it there), then finally you would tap "[1] GSM/(E)GPRS/WCDMA GCF ON", you will see a confirmation that the command succeeded, and as per the instructions from your own device you shall reboot your device using the power buttons and then tap on "restart/reboot". Thats all. At least in my case that should be it for unlocking GSM bands, according for further research I did, the Sprint Galaxy S5 would only work in 3G mode because all the 4G LTE GSM bands are blocked and the ones aren't compatible with the AT&T network (which is the network that I plan to use very soon on this device), so to fix that predicament because I dont want to be stuck on 3G mode I downloaded QPST and QXDM, I had to downgrade my firmware to kit-kat thorugh ODIN (was a b*tch sourcing the original .tar image on the internet, most servers that used to have it no longer had the file and when I was finally about to give up and pay sammobile their $15 to be able to download it from their servers at a speed greater than 15 kbps I finally found a server that was still hosting the NE5 firmware for free!)

For my particular device, beginning on Lollipop Samsung took measures (on the kernel) to prevent users from having access to QPST/QXDM, installing a customer kernel would have given access to QPST/QSDM without having to downgrade firmwares, but the custom kernel that I needed was nowhere to be found, so my only option was to do the firmware downgrade and thanks God that I didn't have the stock Marshmallow bootloader because downgrading would have been impossible then (Samsung implemented a downgrade check - blocker for the S5 starting on Marshmallow) so I was running the BO6 bootloader/baseband, the last ones of the safe bootloader version that allows downgrades.

So anyways, on QPST I made sure that all the 3G bands that I needed for AT&T were indeed enabled, and on QXDM I enabled all LTE bands (thanks to someone who posted the string value to enable all LTE bands for GSM).

So hopefully, when my AT&T SIM card arrives on Thursday Oct 26 not only should I have 3G access, but I also should have 4G LTE access as well, and after my AT&T SIM card arrives I would finally put all this to a test, how effective all this was and most importantly, if this method for domestic GSM unlock really works for me.