Hi, in October I bought this Samsung Galaxy S9+ second hand from a guy. I verified it to be original and be in good working order, lots of screen tests, speaker and camera tests aswell and all checked out. I didn't check for the software updates because I thought I can get them anyway since this guy told be he bought this phone from a local carrier (Telekom Romania), I'm from Romania btw. Recently I found out that Android Pie started rolling out for Note 9 and S9/S9+ so I searched for an update aswell, the only problem is that the software update menu says that my phone is up to date (Android 8.0.0) and my security patch is from August 1, 2018... Last night I looked up my IMEI on a site that I don't know if I can mention and it said that my phone is from the UK and the carrier is: OPEN United Kingdom. I haven't had any problem with my SIM card or WIFI or anything except bad signal outside big cities but I think that's normal. I also tried hooking it up to Samsung Smart Switch on my pc but found no update. If any more details needed leave a reply I will answer ASAP.
My baseband version is: G965FXXU2BRG8
Thank you.
You have an international unlocked model. The OTA updates are are distributed by region via your carrier. It's ultimately up to your carrier when they push your phone the update, however you maybe able to use Samsung's smart switch to update it. Pie was released to the UK region and the Romania region carriers may not have pushed the update yet.
Ok but what about the security patches then? The one I have is from August 2018. Don't they update OTA aswell?
Yes. They come from the same servers as firmware updates, which are distributed by your carrier. If you're not getting OTA updates, you can try removing the Sim card and doing a factory reset. After the initial setup, your sim will reinitialize and reset the CSC group your phone is tied to to ensure its actually requesting firmware for the correct region.
---------- Post added at 01:36 AM ---------- Previous post was at 01:27 AM ----------
Sounds like the phone was previously setup in the UK, factory reset, sim removed, and sold to someone in your country. In that case, because of the order the phone was decommissioned before being sold, it's requesting firmware for another region that your carrier cannot provide. If you remove the Sim and factory reset, that will change your CSC region back to "unknown" and reinserting the Sim will automatically tie the phone to your carrier and region.
hyperblu said:
Yes. They come from the same servers as firmware updates, which are distributed by your carrier. If you're not getting OTA updates, you can try removing the Sim card and doing a factory reset. After the initial setup, your sim will reinitialize and reset the CSC group your phone is tied to to ensure its actually requesting firmware for the correct region.
---------- Post added at 01:36 AM ---------- Previous post was at 01:27 AM ----------
Sounds like the phone was previously setup in the UK, factory reset, sim removed, and sold to someone in your country. In that case, because of the order the phone was decommissioned before being sold, it's requesting firmware for another region that your carrier cannot provide. If you remove the Sim and factory reset, that will change your CSC region back to "unknown" and reinserting the Sim will automatically tie the phone to your carrier and region.
Click to expand...
Click to collapse
Literally tried everything you said step by step, also contacted Samsung (they did nothing) and I'm still stuck on Android 8.0.0 and with an old security patch update. I'll try to update using the sammobile firmware even though my phone is not rooted. I searched my CSC on sammobile and there's no firmware for it
It sounds like Romanian carriers are slow about pushing frequent updates then. I was able to find your firmware on sammobile specifically for your csc, but none of them showed the latest. In this case, you won't receive timely OTA and must circumvent your carrier and do them yourself. Can you confirm if your csc has changed since removing the sim card and performing a factory reset? Or is it still tied to UK region?
Related
I purchase a like-new condition Samsung Galaxy S9+ phone from Amazon Warehouse for international travel coming up in couple days. I figured I would have a better chance of getting an authentic phone from Amazon than from ebay sellers. I received the phone yesterday, and here is the situation with the phone:
- The box of the phone says "unlocked by Samsung"
- The sticker on the back of the phone has the model # SM-G965UZBAXAA and IMEI number of a factory unlocked phone
- The actual IMEI of the phone however shows model # SM-G965UZBAATT, which corresponds to the AT&T carrier locked phone
- When I turn on the phone, it shows T-mobile screen and has T-mobile apps on it
How do I determine whether this is a AT&T phone, or a T-mobile phone or something else? Unfortunately, I do not have either TMO or ATT sim cards that I can use to check which network the phone works on. How do I know whether this phone is unlocked and if it is will work internationally? I am not sure how to explain the imei of the phone coming up with ATT model number, yet the phone shows TMO screen.
Please help as I need to get this resolved today, and don't have time to purchase another phone. Thanks much in advance!!
prince_a1 said:
I purchase a like-new condition Samsung Galaxy S9+ phone from Amazon Warehouse for international travel coming up in couple days. I figured I would have a better chance of getting an authentic phone from Amazon than from ebay sellers. I received the phone yesterday, and here is the situation with the phone:
- The box of the phone says "unlocked by Samsung"
- The sticker on the back of the phone has the model # SM-G965UZBAXAA and IMEI number of a factory unlocked phone
- The actual IMEI of the phone however shows model # SM-G965UZBAATT, which corresponds to the AT&T carrier locked phone
- When I turn on the phone, it shows T-mobile screen and has T-mobile apps on it
How do I determine whether this is a AT&T phone, or a T-mobile phone or something else? Unfortunately, I do not have either TMO or ATT sim cards that I can use to check which network the phone works on. How do I know whether this phone is unlocked and if it is will work internationally? I am not sure how to explain the imei of the phone coming up with ATT model number, yet the phone shows TMO screen.
Please help as I need to get this resolved today, and don't have time to purchase another phone. Thanks much in advance!!
Click to expand...
Click to collapse
put any sim in it and it should work these phones are multi carrier means all the us models are the same if its att imei id say its unlocked since obviously last used was t mobile but if you put any sim in it other than att it should accept it and not say unnsuported sim and or ask for unlock code
to further this as i said the us models are all the same. They have a file called CSC which determines carrier based settings you can put in a tmobile sim and it will repersonalize for tmobile then swap to att and att will show up..
Its the way of the future and actually quite nice as one firmware pretty much covers all carriers other than specific user data which is that carriers apps
it may be unlocked obviously the listing was wrong but xaa is factory unlocked for sims, You can reflash xaa if it is unlocked for non carrier branding,But id put any sim in and see
TheMadScientist said:
They have a file called CSC which determines carrier based settings you can put in a tmobile sim and it will repersonalize for tmobile then swap to att and att will show up..
Click to expand...
Click to collapse
Thanks for your response. So if the previous owner put a T-mobile sim in the AT&T phone, then would it show the T-mobile screen at startup, and also have the T-mobile branded apps?
prince_a1 said:
Thanks for your response. So if the previous owner put a T-mobile sim in the AT&T phone, then would it show the T-mobile screen at startup, and also have the T-mobile branded apps?
Click to expand...
Click to collapse
Yes the csc files are multi carrier the phone will do a New sim inserted please reboot to apply new carrier configuration
and it will reboot and install the inserted sims carrier based bloat apps
TheMadScientist said:
Yes the csc files are multi carrier the phone will do a New sim inserted please reboot to apply new carrier configuration
and it will reboot and install the inserted sims carrier based bloat apps
Click to expand...
Click to collapse
Thanks again! Is it safe for me to do a factory reset on the phone? I wasn't sure if it was rooted and whether a factory reset might brick it. If I do a factory reset, what would it restore to - the AT&T or TMO configuration, or something else?
prince_a1 said:
Thanks again! Is it safe for me to do a factory reset on the phone? I wasn't sure if it was rooted and whether a factory reset might brick it. If I do a factory reset, what would it restore to - the AT&T or TMO configuration, or something else?
Click to expand...
Click to collapse
Yes its safe go into settings and account backup restore it should show factory data reset Thats the proper way to get rig of a google account on the device It will stay as is until a new sim is inserted factory resets have nothing to do with it
TheMadScientist said:
Yes its safe go into settings and account backup restore it should show factory data reset Thats the proper way to get rig of a google account on the device It will stay as is until a new sim is inserted factory resets have nothing to do with it
Click to expand...
Click to collapse
Thank you so much for the information! Highly appreciated!!
TheMadScientist said:
Yes the csc files are multi carrier the phone will do a New sim inserted please reboot to apply new carrier configuration
and it will reboot and install the inserted sims carrier based bloat apps
Click to expand...
Click to collapse
I downloaded the phoneinfo app, and here it what it shows:
Firmware's CSC code: XAA
Active CSC code: TMB
IMEI check shows model ending in: ATT
That made me highly confused as to whether this was a AT&T phone, a T-mobile phone or whether it was originally sold as factory unlocked.
prince_a1 said:
I downloaded the phoneinfo app, and here it what it shows:
Firmware's CSC code: XAA
Active CSC code: TMB
IMEI check shows model ending in: ATT
That made me highly confused as to whether this was a AT&T phone, a T-mobile phone or whether it was originally sold as factory unlocked.
Click to expand...
Click to collapse
So originally it was a att device. Who ever used it used it on tmobile but on xaa which is debloated unlocked
TheMadScientist said:
So originally it was a att device. Who ever used it used it on tmobile but on xaa which is debloated unlocked
Click to expand...
Click to collapse
Under Service Provider SW ver., it shows TMB/XAA/ATT
I am trying to understand what this means, why would it show TMB, XAA and ATT? Does it mean the phone was originally AT&T, then someone installed XAA firmware on it and used it on T-mobile. If that is true, is there a way for me to verify whether the current installed firmware is XAA?
prince_a1 said:
Under Service Provider SW ver., it shows TMB/XAA/ATT
I am trying to understand what this means, why would it show TMB, XAA and ATT? Does it mean the phone was originally AT&T, then someone installed XAA firmware on it and used it on T-mobile. If that is true, is there a way for me to verify whether the current installed firmware is XAA?
Click to expand...
Click to collapse
That is correct. You see it now. The third csc code is the original device. The second is what csc you have running. And the first is or was sim inserted.
Look in settings about phone and software info. At the bottom somewhere it should show you
TheMadScientist said:
That is correct. You see it now. The third csc code is the original device. The second is what csc you have running. And the first is or was sim inserted.
Look in settings about phone and software info. At the bottom somewhere it should show you
Click to expand...
Click to collapse
Yes, what I pasted above is from about phone->software info. It shows the service provider sw version as TMB/XAA/ATT. Thank you!!
I bought a s9+ from swappa around February. I bought my mom one from the same supplier a week ago. At first I was concerned that her's had ATT logo until I realized it would change once a tmobile sim was put in. Her's is now SW ver Tmb/Tmb/Tmb. Then I noticed she is at Android 10.0 UI ver 2.0. I am stuck at Android 9 UI ver 1.0
So It seems I was worried about the wrong phone. It is MY phone that can't get updates. My baseband is:
G965USQU7CSK6 which I believe is an ATT baseband. my SW ver is Tmb/Tmb/Att
I tried connecting to smart switch and it says I am up to date. I tried putting in an at&t sim card (that no longer is in service) and smart switch doesn't complain about anything but it still says it is up to date. Doing OTA while using At&t sim card also says I am up to date. I am CLEARLY not up to date. My last update says Nov.1, 2019.
I have used Odin before...mostly for rooting phone. I haven't rooted since the s5 ( where I could take the battery out ). Little paranoid to use Odin considering I can't take the battery out, but with good instructions I will proceed.
Any help on how to update and especially update on tmobile network would be extremely appreciated.
btw I'm in the US and my model is SM-G965U
-Craig
--UPDATE
I have researched a bit and found that it IS possible to change the firmware over to Tmobile using a patched version of Odin.
I downloaded from
https://forum.xda-developers.com/android/software/patched-odin-3-13-1-t3762572
the 3.13.3_3B_PatcheD.zip
I downloaded G965USQS7CSK3_G965UOYN7CSK3_TMB.zip
from sammobile, which is for Android 9
I would love to be able to use HOME_CSC but that may not work. I could really use some hand holding going through this process.
Is this the correct firmware? Should I be using Android 10 firmware if that is ultimately what I want? HOME_CSC or no? I notice they have the 10 version:
PDA G965USQS7DTB1
CSC G965UOYN7DTB1
as well, which is Android 10 for Tmobile. Also, knox ? will this trip the knox counter thing-a-ma-jig?
Thanks
SOLVED
cw9002 said:
I bought a s9+ from swappa around February. I bought my mom one from the same supplier a week ago. At first I was concerned that her's had ATT logo until I realized it would change once a tmobile sim was put in. Her's is now SW ver Tmb/Tmb/Tmb. Then I noticed she is at Android 10.0 UI ver 2.0. I am stuck at Android 9 UI ver 1.0
So It seems I was worried about the wrong phone. It is MY phone that can't get updates. My baseband is:
G965USQU7CSK6 which I believe is an ATT baseband. my SW ver is Tmb/Tmb/Att
I tried connecting to smart switch and it says I am up to date. I tried putting in an at&t sim card (that no longer is in service) and smart switch doesn't complain about anything but it still says it is up to date. Doing OTA while using At&t sim card also says I am up to date. I am CLEARLY not up to date. My last update says Nov.1, 2019.
I have used Odin before...mostly for rooting phone. I haven't rooted since the s5 ( where I could take the battery out ). Little paranoid to use Odin considering I can't take the battery out, but with good instructions I will proceed.
Any help on how to update and especially update on tmobile network would be extremely appreciated.
btw I'm in the US and my model is SM-G965U
-Craig
--UPDATE
I have researched a bit and found that it IS possible to change the firmware over to Tmobile using a patched version of Odin.
I downloaded from
https://forum.xda-developers.com/android/software/patched-odin-3-13-1-t3762572
the 3.13.3_3B_PatcheD.zip
I downloaded G965USQS7CSK3_G965UOYN7CSK3_TMB.zip
from sammobile, which is for Android 9
I would love to be able to use HOME_CSC but that may not work. I could really use some hand holding going through this process.
Is this the correct firmware? Should I be using Android 10 firmware if that is ultimately what I want? HOME_CSC or no? I notice they have the 10 version:
PDA G965USQS7DTB1
CSC G965UOYN7DTB1
as well, which is Android 10 for Tmobile. Also, knox ? will this trip the knox counter thing-a-ma-jig?
Thanks
Click to expand...
Click to collapse
ok, so I bit the bullet and decided to go ahead. I used
odin 3.14.1_3B_PatcheD.zip just to be sure
I made sure my phone was unlocked: yes it changes carriers if I put in different sim. When in Tmobile sim Settings->Connections->Mobile Networks->Network operators , yes it has a search networks button and it eventually comes up with other carriers so....safe to say I had unlocked phone ( but not samsung unlocked ie. SM-G965U not SM-G965U1)
I used the latest android 9 firmware. and I used HOME_CSC ( even though I did a backup with smart switch b4) Everything went smoothly, and I still have my apps and now I can get an ota security patch for it. Will write back once I am up to Android 10. oh, btw I am still at SW ver Tmb/Tmb/Att , but I've got ota updates so I don't care
cw9002 said:
ok, so I bit the bullet and decided to go ahead. I used
odin 3.14.1_3B_PatcheD.zip just to be sure
I made sure my phone was unlocked: yes it changes carriers if I put in different sim. When in Tmobile sim Settings->Connections->Mobile Networks->Network operators , yes it has a search networks button and it eventually comes up with other carriers so....safe to say I had unlocked phone ( but not samsung unlocked ie. SM-G965U not SM-G965U1)
I used the latest android 9 firmware. and I used HOME_CSC ( even though I did a backup with smart switch b4) Everything went smoothly, and I still have my apps and now I can get an ota security patch for it. Will write back once I am up to Android 10. oh, btw I am still at SW ver Tmb/Tmb/Att , but I've got ota updates so I don't care
Click to expand...
Click to collapse
I am now at the same baseband version as my mom. Everything worked perfectly. I suggest you go with the least change possible to get to the point that you are able to do OTA updates. For me this was going to the latest Android 9 that they had at sammobile since I was on Android 9 and going with the Tmobile version. I hear the carrier doesn't even matter these days, but I decided I wanted to make sure it was Tmobile compatible so I chose the Tmobile version from sammobile. Happy trails to you in your endeavors. Hopefully you can learn something from mine.
Hey, I really want to thank you for this! I had the same issue and was exploring similar solutions. After several days of researching alternate plans, I was about to give it up as too risky until I found your post - by googling for hints: "SW ver. TMB/TMB/ATT"! You helped me take the dive, and I'm now happily past having a second-hand S9 (sm-g960u) that wouldn't do an OTA update. After a flawless flash, my first OTA request got me to Android 10, (UI 2). now I have a follow-up update scheduled for the wee hours. (And, yes, I'm still at "TMB/TMB/ATT".)
Perhaps like you, I started by investigating the possibility of flashing the UNLOCKED ("U1") firmware. After learning it was possible with the _patchedD Odin, it still scared me enough that I decided on a more conservative approach and followed your exact advice. I especially appreciated your plan to flash NOT the latest update, but the last Android 9 TMB update. That turned out to correspond to the ATT version on my phone, making TMobile either unable or unwilling to offer an OTA update.
History: This is my third used S9. While all were sold as UNLOCKED, only the first had the "U1" model suffix (SM-g960u1). When the second one booted up as a TMobile phone, I felt tricked - but also lucky that I got the right carrier. That's when I learned about the difference in model numbers. As you noted the U1 firmware is factory unlocked - attached to no carrier. When my third phone booted up with a Verizon greeting I figured I could be facing trouble - even though it accepted my TMB sim card.
The seller explained to me that my phone was part of a batch of ATT phones, all "SIM unlocked" using a Verizon sim card. I think sellers of phones with claims to be unlocked should be required to specify whether FACTORY or SIM unlocked.
Hope this great contribution of yours will continue to help others.
Hello,
I have a SIM unlocked S21 from Xfinity Mobile that I'm now using on Verizon Wireless. I need to change the CSC to VZW, anyone know how? I tried all the dialer codes, and also SamKEY but no luck so far.
SamKEY says "unsupported firmware, please downgrade your firmware".
Since January 2021, it's not easy to change CSC, some people do it by flashing firmwares then block whatever app checks SIM & CSC compatibility.
You can check this thread if you're into action.
Thanks, I tried that but somehow it ignores that the VZW SIM card is VZW, and it keeps the CSC as CCT/CCT/CCT.
Even putting in an AT&T sim card, it still keeps it as CCT/CCT/CCT. The carrier name is stuck as "Xfinity Mobile" also, no matter the SIM.
I wish Samsung would implement the "BYOD" thing already for this phone.. Or maybe SamKEY will work eventually...
What's interesting is that it changes the APN to the correct one automatically for the 3 SIM cards I've tried (VZW, CCT, ATT)
Firmware bug I guess, or Samsung has not yet fully implemented the "BYOD" feature referenced here:
Move your Galaxy phone to a different service carrier
If you unlock your phone to use with another carrier, it's easy to take advantage of all your new carrier's features without losing any of your data.
www.samsung.com
UPDATE: SamKEY worked!!
I was able to change the CSC to the correct carrier!
quadrun1 said:
UPDATE: SamKEY worked!!
I was able to change the CSC to the correct carrier!
Click to expand...
Click to collapse
how many credits do I need to change CSC?
On the samkey page it says that you need 8 credits
No, if I remember correctly it's only 1 credit to change the CSC.
See here:
https://www.reddit.com/r/GalaxyS21/comments/lm0at9
Long post here sorry people,now guys I would really appreciate your input as I'm new to unlocking phones and flashing fw etc
I recently ordered a brand new handset that was sold to me as sim free unlocked uk version as I'm from the uk ,when I recieved the phone yesterday all seemed good and new and unused,so I went into software information in the phone to check if it was really a uk handset i expected to see XEU/XEU/XEU OR BTU/BTU/BTU like my other uk phones,but the service provider sw ver had weird csc codes I've never seen on a uk handset,its was
AUT/AUT/O2U now after doing some research the code on the right O2U is the original csc and cant be changed and O2U is o2 uk so the phone was a locked and branded o2 uk phone I guess?so I'm assuming the csc was originally O2U/O2U/O2U or maybe XEU/XEU/O2U? I may be wrong here ,but AUT/AUT from my small bit of research is a Switzerland unlocked firmware,so what has the seller sold me?
IS my phone a uk locked branded O2 handset,that the seller had unlocked so the phone would work with any sim card ,and did he flash swiss unlocked firmware?if so why?and how can I be sure what the original csc was for the first 2 codes?i know the 3rd code is O2U so if I wanted to get the phone back to the original state if I needed to send it in for warranty?or would a phone like this still be in warranty?
Now I did say this was going to be a long post I apologise guys.so anyway at this point the CSC codes are AUT/AUT/O2U then I put my uk ee sim card into the handset for the first time to check if the phone really is unlocked,after inserting the sim card a message came up saying please factory reset to make the sim work or something along those lines, but before I did that I went back into software information to see if the csc had changed and it had changed to AUT/XEU/O2U so this was weird,then I factory reset the phone, after the factory reset it prompted another factory reset so I clicked ok
Then after the reset was done I went back into software information and the csc had changed again for the 3rd time, this time to XEU/XEU/O2U and it's been on this ever since,do uk o2 phones have this csc?with XEU/XEU/O2U or would they be O2U/O2U/O2U? again I apologise for the long post but if you guys could tell me what my phone is and what has been done to it would be helpful,and is my warranty still intact if the csc has changed automatically by me inserting my sim card?and if I wanted to revert the phone back to how it was before it was unlocked what would the csc be and how easy is it to revert it back to the 3 original csc what ever they may have been,
Ok guys I probably should have just called samung before making this thread,but I just called them and gave them the imei number and they said it's a uk 02 locked phone that is unlocked now for any sim as I'm using my ee sim.so I dont know why the csc said AUT/AUT/O2U .them changed to AUT/XEU/O2U then changed to XEU/XEU/O2U
But if I wanted to turn my phone back into a locked o2 phone again not that I would probbly need to do this but would the phone have been branded or non branded o2 phone.and what would the csc be and would that change automatically from XEU/XEU/O2U to something else if I were to flash android 10 firmware for a uk o2 phone using Odin would that change the csc back to what it was originally before I recieved the phone?or would I have to do something else to get the original csc back?
I think the O2 carrier firmware was changed to unlocked/unbranded
If I wanted to take it back to o2 like it was originally how would I do that? Could I just flash this 02 android 10 fimwhere using odin and that will change the csc back to whatever it was originally will this O2 file make my phone 02and locked o2 again?and would I need an o2 sim card to make the csc change back to the original csc .or will it auto change after flashing the o2 firmware?
Download Samsung Galaxy Note9 SM-N960F O2U United Kingdom (O2) N960FXXS8FUF5 firmware
Fast download latest Samsung Galaxy Note9 firmware SM-N960F from United Kingdom (O2) with N960FXXS8FUF5 and Android version 10
www.sammobile.com
What are the "TMB" and "USC" in the "Update info" links?
They're both US unlocked.
doc.samsungmobile.com/SM-S918U1/TMB/doc.html
doc.samsungmobile.com/SM-S918U1/USC/doc.html
They correspond to the CSC (Consumer software customization) determined by your SIM card. If you're on T-Mobile, you will see TMB. If your'e on US Cellular, you'll see USC. On an Unlocked U1 phone, there may be carrier specific changes with an update.
Guyinlaca said:
They correspond to the CSC (Consumer software customization) determined by your SIM card. If you're on T-Mobile, you will see TMB. If your'e on US Cellular, you'll see USC. On an Unlocked U1 phone, there may be carrier specific changes with an update.
Click to expand...
Click to collapse
And if someone changes their service, can the old updates that were for the old carrier pose a potential problem now that they're with the new carrier and receiving their updates?
When you remove the old SIM card and insert the new one, it will ask you to restart to apply the correct settings for your carrier. The SIM does the work for you.
Guyinlaca said:
When you remove the old SIM card and insert the new one, it will ask you to restart to apply the correct settings for your carrier. The SIM does the work for you.
Click to expand...
Click to collapse
I assumed that was just changing the APN and changing the carrier settings. But it actually undoes old updates and reinstalls them?
No. Every firmware and update has CSCs built in. It doesn't revert the software, it just activates features specific to your carrier (based on SIM). It's a partition of sorts.
Guyinlaca said:
No. Every firmware and update has CSCs built in. It doesn't revert the software, it just activates features specific to your carrier (based on SIM). It's a partition of sorts.
Click to expand...
Click to collapse
1) So when one switches from carrier one to carrier two, what happens to all the past updates that are associated with carrier one?
2) If the SIM card is removed and a new one isn't inserted (for instance if one's upgading to a new phone), will the future updates be "generic"? (Obviously when the old phone is in one's home with a wifi connection.)
1. Each U1 software update contains all US carrier CSC partitions. If you update from A7 to A8, and change SIM cards, you'd remain on A8, but the CSC partition switches to the new carrier. There is never any rolling back, merely switching from one partition to another.
2. If you remove the SIM, your phone updates using the previously set CSC. If you used a T-Mobile SIM, it stays on TMO. The default CSC on U1 is XAA and there's little reason to go back to it, though it can be done with certain tools.
Guyinlaca said:
1. Each U1 software update contains all US carrier CSC partitions. If you update from A7 to A8, and change SIM cards, you'd remain on A8, but the CSC partition switches to the new carrier. There is never any rolling back, merely switching from one partition to another.
2. If you remove the SIM, your phone updates using the previously set CSC. If you used a T-Mobile SIM, it stays on TMO. The default CSC on U1 is XAA and there's little reason to go back to it, though it can be done with certain tools.
Click to expand...
Click to collapse
Thank you.