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G981U and G981U1 Firmware Links and Flashing Discussion Here

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tonysunshine

Senior Member
Jun 4, 2009
118
18
could I in theory flash this rom

then flash the AT&T USERDATA on top of it?
I'm basically trying to have a rooted S20 with AT&T wifi calling enabled
 

iBowToAndroid

Senior Member
Nov 9, 2010
4,647
1
1,433
Twin Cities MN
could I in theory flash this rom

then flash the AT&T USERDATA on top of it?
I'm basically trying to have a rooted S20 with AT&T wifi calling enabled
That's for the Ultra, not the regular S20
 

NJ_RAMS_FAN

Senior Member
Sep 28, 2011
885
96
North Bergen, NJ
Hi. Long time I haven't been here. I don't even know where the search button is. Heres my question. My friend handed me a good condition ultra locked to att. I want to use it for tmobile but I can't cause it locked. Att doesn't want to unlock even though he paid it off. My friend is going to find them..

This might be dumb question, but would flashing unlock samsung firmware actually also unlocked the network on phone? Lol. Or I need to unlock first via att code???
 

iBowToAndroid

Senior Member
Nov 9, 2010
4,647
1
1,433
Twin Cities MN
Hi. Long time I haven't been here. I don't even know where the search button is. Heres my question. My friend handed me a good condition ultra locked to att. I want to use it for tmobile but I can't cause it locked. Att doesn't want to unlock even though he paid it off. My friend is going to find them..

This might be dumb question, but would flashing unlock samsung firmware actually also unlocked the network on phone? Lol. Or I need to unlock first via att code???
No, flashing U1 will not magically unlock the phone. You need to actually get the unlock code. I can recommend a professional 3rd party business to do it, if AT&T refuses
 

alirz

Senior Member
Oct 1, 2014
165
19
Someone please remind me. I'm looking to manually flash fw from the February UI3 update to the ui 3.1 March update for the u1 model.
Odin seems to suggest to remove google and samsung account from the phone before the flash. Is that really necessary?
 

Qusyairi626

New member
Dec 27, 2016
1
0
Hi, i just want to ask why does my phone got Sprint in my Contact List, but i didn't add in. My phone model number SM981U and Unlocked. How do i remove it because i live in asia.
 
Last edited:

bocondo

Senior Member
Apr 21, 2008
108
16
I have T-Mobile version of S20, which was unlocked long time ago. I recently switched to Verizon and the phone working perfectly fine. This morning I received security update for May 2021 from T-mobile and after that phone is not able to connect to network.
I used OP's version of Odin and VZW Firmware downloaded from Sammobil and was able to revive the phone. Thanks a bunch OP!
 
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nolabowler

Member
Aug 19, 2010
49
1
i need help please........ I have a S20 5g SM-G981U T-Mobile phone that is unlocked. It has tmobile bloat on it......now for the issue.... I am on AT&T and have tried to flash U and U1 variants to get a Stock AT&T bloated phone with no success. It boots with the tmobile splash screen on every U firm ive used. I can get U1 with no bloat from anyone which i think is basic samsung firm. i dont like all of att bloat but do like some of the carrier enabled apps, so im looking to flash the stock att firmware. Also no matter what the carrier version always says TMB/TMB/TMB/. i have my att sim card in now and everything works, but its wont flash to a stock att rom with att carrier settings. Can anyone point me in the right direction? i have tried the OP files and method several times.
 

iBowToAndroid

Senior Member
Nov 9, 2010
4,647
1
1,433
Twin Cities MN
i need help please........ I have a S20 5g SM-G981U T-Mobile phone that is unlocked. It has tmobile bloat on it......now for the issue.... I am on AT&T and have tried to flash U and U1 variants to get a Stock AT&T bloated phone with no success. It boots with the tmobile splash screen on every U firm ive used. I can get U1 with no bloat from anyone which i think is basic samsung firm. i dont like all of att bloat but do like some of the carrier enabled apps, so im looking to flash the stock att firmware. Also no matter what the carrier version always says TMB/TMB/TMB/. i have my att sim card in now and everything works, but its wont flash to a stock att rom with att carrier settings. Can anyone point me in the right direction? i have tried the OP files and method several times.
Do you not get the popup prompt to reboot to apply new carrier settings, when you insert an AT&T SIM while on U firmware?
 

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    For those who aren't already aware, G981U is the model number of all of the US carrier versions of the S20. The G981U1 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. A "U to U" or "U1 to U1" flash does not require a factory reset, but changing from one firmware to the other will require one. 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 (or haven't done it in a long time), 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=305577
    U1 firmware: https://www.androidfilehost.com/?w=files&flid=305578

    (Quebec tends to be the fastest download mirror, if it gives you that option)

    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:

    AIO = Cricket (not available via SamFirm/Frija)
    ATT = AT&T (not available via SamFirm/Frija)
    BST = Boost Mobile
    CCT = Xfinity Mobile (Comcast)
    CHA = Spectrum Mobile (Charter)
    SPR = Sprint
    TMB = T-Mobile
    TMK = Metro PCS
    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
    1
    Pre-release notes:

    1. I do not have one of these and do not plan to acquire one, so I have no idea if anything can actually be flashed at this moment - I'm just providing the firmware. Like all other models, I'm assuming patched Odin is needed for this, but it wouldn't surprise me if a new version is needed for this specific device. There's only one way to know though, so as soon as someone gets their hands on one and can try this, please let us know.

    2. I don't know if using the HOME CSC will actually save data. I don't get access to that file straight from the source - I have to decompile the regular CSC, remove the parts that initiate the factory reset, and then re-compile it. Based on the S10 and Note 10, I've done what I think will avoid a factory reset. But the S20 has some new partitions, so we won't know for sure until someone tests it. So if you're willing to be that guinea pig, you're responsible for taking proper steps to avoid an FRP lock, make sure your data is backed up, etc
    1
    I want to flash my unlocked samsung s20 so I can use the ATT Volte and wifi calling but will rom eventually get released
    If you're saying that you want AT&T apps and bloatware and features, then all the files that you need are already linked in the OP
    1
    I'm worried that I already know the answer, but i'm asking it anyways. I'm currently on a SM-G981N (South Korean version), which is a Snapdragon865 phone. I'm wondering if I can change my firmware to the SM-G981U version to get rid of the bloatware on my phone. For what I read for other phone's this wouldn't work. Perhaps I should start looking for an unbloated SM-G981N rom? Thanks!
    I'm assuming the flash would fail. But there's only one way to know for sure
    1
    Got it figured I used the wrong firmware
    Oh okay :)