G988U and G988U1 Firmware Links and Flashing Discussion Here

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iBowToAndroid

Senior Member
Nov 9, 2010
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I've tried but I never get the pop up to install the carrier software when I insert the AT&T sim card upon reboot.

I removed my sim card before flashing... Flashed with XAA AP,BL,CP and non home CSC files (G988U1UES2DUE2). Upon reboot I inserted the AT&T sim card and its just connects to service, no pop up.
That's a known issue with recent versions of the U1 firmware. If you don't get the popup, it won't convert
 

creative70

Senior Member
Jul 2, 2010
56
16
OnePlus 7 Pro
I flashed G988U1 firmware on G988W without erasing and 5G/WifiCalling were working on my S20 Ultra. However, when I erased the device and installed with CSC and not the home CSC, the network would not connect to 5G and just LTE+. This is ridiculous as Rogers is not letting you enjoy enhanced features for devices purchased outside of Canada. Now I'm back to G988W.
 

mchu519

New member
Oct 30, 2021
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I just realized a few days ago my ATT variant Galaxy S20 Ultra was still on the June 2020 update. I realized I couldn't get OTA update. Thought I dive back into the good old ODIN and FRIJA to get the latest update and while at it flash to the T-Mobile CSC. I got the Odin3 v3.14.1_3B_PatcheD.exe and and flashed the version shown in the attached screenshot.

1635571156375.png

I was able to successfully update to the latest with "Android security patch level 10/1/2021". Sadly the "Service provider software version" is still ATT/ATT/ATT and not TMB.

0.jpg


I'm just glad I was able to get the latest update. Would've been nice to get rid of all the ATT bloatware since I haven't been on the ATT network for awhile.
 

iBowToAndroid

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Nov 9, 2010
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Twin Cities MN
I was able to successfully update to the latest with "Android security patch level 10/1/2021". Sadly the "Service provider software version" is still ATT/ATT/ATT and not TMB.


I'm just glad I was able to get the latest update. Would've been nice to get rid of all the ATT bloatware since I haven't been on the ATT network for awhile.
All of the information for changing from one carrier's bloatware to another, as well as completely removing bloatware, is right in the OP
 

getm0ney

New member
Jun 18, 2012
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I have a TMO g988u on Android 11. I followed the steps and flashed it to u1 but never got the Sim pop up.

Flashing it back to 988u with ATT userdata and it's still got TMO splash and whatnot. I need ATT wifi calling cause service sucks at my house, is it not possible anymore?!
 

iBowToAndroid

Senior Member
Nov 9, 2010
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I have a TMO g988u on Android 11. I followed the steps and flashed it to u1 but never got the Sim pop up.

Flashing it back to 988u with ATT userdata and it's still got TMO splash and whatnot. I need ATT wifi calling cause service sucks at my house, is it not possible anymore?!
If you don't get the popup, then no, there's not much else you can do to force the bloatware conversion. You could try flashing and resetting with and without the SIM inserted - it may make a difference
 

Predakays

Member
Sep 25, 2015
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Hi! Maybe this is gonna be a dumb question but I just want to be sure before I make the change.

I've got a S20 ultra 5g sm-G988U... It's from AT&T. It was locked but I got the unlock code and now It's unlocked.
I couldn't get the newest updates because I'm not in USA. So I updated manually with ODIN.

My question is:
If I change my device to Sm-G988U1 I'm going to get OTA updates from Samsung? Like any other exynos samsung?

Also
Change the version from SM-G988U to SM-G988U1 WILL AFFECT THE NETWORK CONNECTION? I mean lost signal connection to my current carrier (outside of USA).
 

iBowToAndroid

Senior Member
Nov 9, 2010
5,105
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Twin Cities MN
My question is:
If I change my device to Sm-G988U1 I'm going to get OTA updates from Samsung? Like any other exynos samsung?

Also
Change the version from SM-G988U to SM-G988U1 WILL AFFECT THE NETWORK CONNECTION? I mean lost signal connection to my current carrier (outside of USA).
1. I don't know if you'll then get OTA updates. It depends on what the Service Provider codes change to, after the flash. If they remain as ATT, then you probably will not get updates, and you'll have to manually flash every update. If the codes change to something else, then you probably will get updates

2. No, it shouldn't affect the network connection
 
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GSXeclipsePSI

Senior Member
Jul 8, 2011
122
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Hudson, FL
Happy New Year everyone!

I get impatient easily and have free time on my hands.

I would like to use the U1 beta One UI 4 on my 988U

So I've done tons of flashing on Samsungs so I know how to do everything. Just want clarification on the process.

So download the latest U1 with XXA? or my carrier TMB (don't mind the bloat)

Then do I start flashing the Beta releases? 1-2-3?

will any of this trip KNOX? I don't believe it would since it's stock.
I really enjoy Samsung Pay etc and don't wanna risk it.


Can someone use my above plan out into a process of steps that verifies how I am doing it?

1- Flash newest U1 (XXA or TMB?) ROM via Odin patched using HOME CSC to keep data (Already made recovery with SmartSwitch)
2 - Start flashing Beta 1, 2, 3 which should keep my data (I can do this via SDcard or Odin?)
 

gregou

Senior Member
Dec 20, 2006
680
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Nantes
Samsung Galaxy S22 Ultra
I have a question : So basically i have the G988U1 model and i live in France. I would like to get Android 12 as Samsung doesn't seems in a hurry to released it for this model... when the Verizon variant already got it.. which is dumb but anyway..

So i downloaded the U VZW Android 12 firmware on Frija, if i flash the U VZW firmware on my U1 model, all will be ok right ? (i don't any VZW Sim card obviously so i don't know it's mandatory to get this flashing process working...

Any idea ?
 

iBowToAndroid

Senior Member
Nov 9, 2010
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Twin Cities MN
I have a question : So basically i have the G988U1 model and i live in France. I would like to get Android 12 as Samsung doesn't seems in a hurry to released it for this model... when the Verizon variant already got it.. which is dumb but anyway..

So i downloaded the U VZW Android 12 firmware on Frija, if i flash the U VZW firmware on my U1 model, all will be ok right ? (i don't any VZW Sim card obviously so i don't know it's mandatory to get this flashing process working...

Any idea ?
Yes, it'll be fine
 

iBowToAndroid

Senior Member
Nov 9, 2010
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Is root working with android 12? G981U1
Your device has to be on bootloader 1 in order to unlock the bootloader, and therefore root. Once you're already unlocked + rooted, then you can flash a modified firmware that will allow you to retain unlock + root, while upgrading to newer versions.

But if your device already has Android 12 and has never been bootloader unlocked or rooted, then no, there is no working method
 
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    For those who aren't already aware, G988U is the model number of all of the US carrier versions of the S20 Ultra. The G988U1 is the model number of the same device, but sold by Samsung SIM unlocked and with no carrier bloatware. Firmware is 100% interchangeable among these models: any U or U1 firmware version can be flashed to any U or U1 device at any time, assuming that you're not trying to downgrade the bootloader. Also, U firmware is identical for the 4 base files (AP, BL, CP, CSC) for each individual build, no matter which carrier it comes from. So if you download 2 different carrier versions of the exact same build, the 4 base files will be identical. Where the firmware differs is in the USERDATA file - that's where the carrier bloatware and customizations reside.

    Manual Odin flashing is designed for those who:

    - want to manually update to a newer version of U firmware on their U device, either because they don't want to wait for their carrier's OTA or because OTAs aren't working on their device, or a different carrier got a new feature/patch before they did
    - want to flash U1 firmware to their U device
    - want to convert from U1 firmware to carrier U firmware
    - want to convert from one carrier's U firmware (with all apps and bloatware) to a different carrier's U firmware (with all apps and bloatware)

    For those who aren't already aware, anyone can now download firmware for almost any Samsung device any time that they want, via SamFirm or Frija. There are threads and info about them here on XDA so I won't waste time explaining - do a search if you're not already familiar with these tools. But they only provide whatever the latest/newest/current version is - nothing older. I pay for a subscription to a site that gets the official releases (usually) before they hit SamFirm/Frija, so that's where my files come from. However, I don't have unlimited bandwidth on the site, and it's also quite time consuming to download the files, zip them up, and upload them to AFH. And, I do threads like this for every single Sx and Note x model - so I won't be uploading every single version. The only full builds that I upload are ones where I get access to a new bootloader and/or Android version early, before they hit SamFirm/Frija.

    This is not a "beginner's guide to Odin flashing" -type post/thread, so I won't list basic, step-by-step flashing instructions. My threads are geared towards those who already know what they're doing. If you're new to manually flashing Samsung firmware, I recommend you consult one of those "beginner's" guides- there are tons of them here on XDA.

    Happy flashing!

    U firmware: https://www.androidfilehost.com/?w=files&flid=305574
    U1 firmware: https://www.androidfilehost.com/?w=files&flid=305575

    Notes:

    - DON'T QUOTE THE OP WHEN YOU REPLY, kthx

    - I have lots of threads just like this one for other Samsung flagships, if it interests you. For those who have already made use of my previous threads for a different device and are upgrading to an S20, welcome back :)

    - My zips are compressed extra small for space and bandwidth savings. The default Windows extractor can't handle it, so you'll need a 3rd party tool like 7zip, WinRAR, etc

    - My naming method for folders on AFH is: build - bootloader - Android version
    So "SAT - 1 - 9.0" means the full build number ends in SAT, it's bootloader version 1, and it's Android 9.0. When bootloader and Android versions increment, the first build to have those changes will have its folder notated appropriately.

    - HOME CSC file keeps data intact; using the other CSC will wipe data. Flashing USERDATA will also wipe data

    - Since AT&T doesn't allow their firmware to be publicly available (for any of their devices), I'll try to always upload at least one USERDATA per bootloader increment for AT&T (and Cricket, if they get this model). I'll also upload any full builds if AT&T is the only carrier to get that specific build, because you won't be able to find the files anywhere else.

    - For identifying USERDATAS, and to know what region/CSC to use in SamFirm/Frija:

    ATT = AT&T (not available via SamFirm/Frija)
    CCT = Xfinity Mobile (Comcast)
    CHA = Spectrum Mobile (Charter)
    SPR = Sprint
    TMB = T-Mobile
    USC = US Cellular
    VZW = Verizon (available via SamFirm/Frija, but Manual Entry is required - Auto will not work)
    XAA = U1 firmware

    - the correct procedure for switching from one carrier's firmware to another is:
    1. Flash full U1 firmware package including non HOME CSC
    2. Upon boot, insert a SIM of the carrier whose firmware you want
    3. Watch for the popup that says "reboot to apply new carrier settings" etc, and do it
    4. After that restart completes, reboot back to Download mode and flash the full U firmware package, with the USERDATA file of the carrier whose firmware you want
    2
    Interesting. Flashing the U CSC is all that's needed? Any OTA issues?
    Sorry for delay
    No.... If you do U1 ( or in my experience anything besides basic original firmware) then no OTA. BUT at least calling features can work
    2
    @iBowToAndroid Just curious -- when flashing ATT, for example if you wanted to go back to the original completely stock ATT firmware , is it even completely possible? Are the TMB and USC firmware downloads the same minus the ATT userdata? If the USC and TMB or XAS (those are the ones I saw) aren't the same then which is the best one for flashing an ATT branded phone?? Thanks
    All those answers are already in the OP.

    1. Yes it's possible

    2. Yes they're the same

    3. Best one for flashing ATT firmware is ATT files

    Thanks, would I need to flash userdata?
    Nope. USERDATA only exists on U firmware
    2
    In Odin, there are 4 components to flash, including the csc or home csc. I am wanting to flash the u1 unbloated version but use the branded csc to keep the carrier features.
    All U firmware pieces are identical, for each build - no matter which carrier it's from. So there is no such thing as an "AT&T CSC". So you can flash the CSC from any released build of Android 11 U firmware, combined with the rest of the files from any released build of Android 11 U1 firmware.
    2
    Just wanted to say a couple things. First, thanks for the work the OP and others have put in making this info and the ROM's available!

    Second, it's been a while since I've flashed a ROM so I was a little rusty, here's a couple tips that may help others. There's no power button, obviously. Volume down and Bixby key force power off. Volume up and Bixby key boot the phone into recovery mode. At one point I ended up with a failed copy to the phone from Odin that horked things up, got a checksum failure. At that point Odin wouldn't download any of the images. I used the patched version of Odin (several threads with it easily searchable on XDA). The patched version fixed it (I think it bypasses some of the safety checks) and I was good to go again.

    Like some others, I was having trouble getting the carrier firmware to stick, I kept ending up with XAA after flashing the carrier stuff, including that AT&T folder. It was driving me nuts. I'm on Firstnet and I got thinking that may be the issue, since it's got lots of quirks. I'm guessing the Firstnet SIM wasn't triggering whatever the firmware needed to see in order to install that AT&T version (even though it's basically AT&T although Firstnet has a separate network core from AT&T).

    I tried popping in a Verizon SIM I had and that triggered the install of all the Vz crap and it all worked as expected. So knowing that the process worked but just wasn't working right with Firstnet, I ordered a couple AT&T sim cards. I reflashed and then inserted the AT&T sim and it triggered the carrier update and then successfully flashed the AT&T firmware. I was also stoked that it worked with an unprovisioned sim card, I was hoping that would work and I wouldn't have to sign up for service just to flash my phone.

    After this I popped in my Firstnet sim and everything's been working perfectly. I'll also note that for those on Firstnet and are subscriber paid, you can login to the admin portal and manually update your device IMEI yourself. Even after I had my sim in my new phone it was still showing my old phone until I manually updated the IMEI in the portal. I'm guessing you're not going to get all the features without updating that.

    So, after all that, on Firstnet, with AT&T firmware and my IMEI number updated, I'm getting all features working, VoLTE, Wifi Calling, etc. I'm super happy with it and also am seeing a large increase in speeds over running on the XAA firmware. I'm guessing on XAA I'm either not getting CA or Priority, or both. I'm seeing about triple the speed on the carrier firmware. YMMV since Firstnet is a unique beast but wanted to throw my experience out there in case it helps anyone else.