Database Develop

[MOD] Exynos T-Mobile CSC Wifi Calling, VoLTE etc for N950N / N950F

* 2018 January 19 massive update*
After days and nights 3 months of trying to get this to work on my Korean N950N's base, I realized that it is either missing components or has different incompatible versions of some files compared to the N950F (noticing that both TEKHD's pack and the CSC changer mega zip specify being for the F international models) and flashed NEMESIS N950F-based ROM, then this on top of it. finally figured out what needed to be changed to get this working on the N variant.
Quick summary:
Near stock T-Mobile N950U TMB CSC (unencrypted so feel free to tweak the CSC features if you wish)
swapped bootup and shutdown videos to unbranded Note 8
by swapping bootup and shutdown videos, T-Jingle does not play on bootup or shutdown
enabled Smart Call caller ID
enabled FM radio menu but more research is needed to confirm if the Exynos 8895 has an FM radio chip or not
enabled message type visible in MMS/SMS apps
enabled hardware version in system menu
enabled editing of APNs
removes all Korean carrier apps from N950N variant (SK Telecom, kt Olleh, and LG U+ apps)
VoLTE and Wifi Calling work for both Exynos variants. On N950N firmware, an N950F-based kernel still needs to be used at the moment but this is being researched further - I would like the zip to stand on it's own.
There may be some other minor tweaks that I can't remember off-hand but this is by and large stock N950U's CSC features.
For N950N firmware: Everything works including wifi calling* as of version 9m1, N950F-based kernel is still needed for init.rilepdg.rc - will be researching to see if I can get this to load from /system/ instead so no kernel mod or separate kernel is necessary
For N950F firmware: Everything works, including wifi calling.
Download Link:Exynos Note 8 T-Mobile VoLTE + Wifi Calling patch version 9m1
*EDIT 2018-01-19*
Total overhaul from the original - version 9m1 uploaded which works on both N950F and N950N firmware, though at the moment on the N950N a custom kernel (N950F-based) still needs to be used to get T-Mobile Wifi Calling to connect.
*EDIT 2017-09-28*
Minor script tweak update (replaced link) because I noticed sometimes it was defaulting to XAA instead of TMB. Now it will definitely always default to TMB.

So to simplify I can use this on a N950F on Tmobile and still get all the functions like from a Tmobile variant?

Clarkkent434 said:
So to simplify I can use this on a N950F on Tmobile and still get all the functions like from a Tmobile variant?
Click to expand...
Click to collapse
Yes, you'll get wifi calling, VoLTE, HD Voice dialer, etc. I didn't include the T-Mobile bloatware apps but I think you can download them from the Google Play Store separately if desired.

Looks like you finally got it working. Cheers!
I didn't check your Q&A thread on it, but did you keep your native bootloader (N950N) or did you just go all N950F?

Thanks for figuring this out, working great for me. I couldn't stand the tmobile jingle on start up. Easy fix, just removed the related files before flashing.
My N950F didn't have the shutter sound toggle. I just got rid of the shutter audio file but after flashing this I now have the toggle.

Kamikaze_Ice said:
Looks like you finally got it working. Cheers!
I didn't check your Q&A thread on it, but did you keep your native bootloader (N950N) or did you just go all N950F?
Click to expand...
Click to collapse
Thanks! Yes kept my N950N bootloader and modem. Roughly around the same time I first flashed the 950F ROM though my LTE signal changed to terrible, and I haven't figured out yet what the cause is - even tried going back to full stock N950N with Odin and speeds/signal strength are abysmal. My old Note 5 is running circles around this thing LTE-wise.
shouren04 said:
Thanks for figuring this out, working great for me. I couldn't stand the tmobile jingle on start up. Easy fix, just removed the related files before flashing.
My N950F didn't have the shutter sound toggle. I just got rid of the shutter audio file but after flashing this I now have the toggle.
Click to expand...
Click to collapse
Glad it helped! Yeah I am not a big T-jingle fan either but it was a nice immediate sign that the zip worked. That toggle can be in either the others.xml or in framework-res.apk -> res-> bools.xml as I found out tonight.

Is this a T-Mo only thread.. any info for AT&T here or if not.. know where to go? Also have N950N - after Renovate Rom registers as 950F and looking to get it working super fast on at&t?

So if I stay on the stock N950N KT firmware, all I will be missing is WiFi Calling? Everything else works now? Wasn't sure from the way you worded it in the OP. Do I have to flash an N950F ROM to make things work? Should I just flash the stock N950F ROM if I just want things stock instead of a custom ROM?

Comp1demon said:
Is this a T-Mo only thread.. any info for AT&T here or if not.. know where to go? Also have N950N - after Renovate Rom registers as 950F and looking to get it working super fast on at&t?
Click to expand...
Click to collapse
My patch is for T-Mobile, but it includes the AT&T files as well. You could change a few tiny script things to make it set the CSC to ATT, though I have no way to test if it will work as well, plus I guess you have to call AT&T and have them enable VoLTE and wifi calling on their end for your IMEI.

FMXP said:
So if I stay on the stock N950N KT firmware, all I will be missing is WiFi Calling? Everything else works now? Wasn't sure from the way you worded it in the OP. Do I have to flash an N950F ROM to make things work? Should I just flash the stock N950F ROM if I just want things stock instead of a custom ROM?
Click to expand...
Click to collapse
Yes, on the stock firmware with this patch you will get all the goodies except for WiFi calling. I have not yet figured out what's missing between the 950N and 950F firmwares that allows the patch to make wifi calling work on the F only. If I can get some more time to figure it out I will make an updated patch and I'll probably switch back to 950N firmware because I'm having awful LTE suddenly and want to eliminate everything in the 950F ROM as a culprit.

FMXP said:
So if I stay on the stock N950N KT firmware, all I will be missing is WiFi Calling? Everything else works now? Wasn't sure from the way you worded it in the OP. Do I have to flash an N950F ROM to make things work? Should I just flash the stock N950F ROM if I just want things stock instead of a custom ROM?
Click to expand...
Click to collapse
Yes exactly, everything besides the wifi calling will work. If I can get some more time to figure out what's missing between the F and N firmwares I will update the patch to include the necessary files for our stock N firmware to get it working as well.
I'd rather stick to N firmware if possible to avoid any issues with F ROM incompatibilities but at the moment I'm trying to figure out why my LTE signal suddenly sucks. Odin'ed back to full stock and it still sucked so I am spending most of my free time troubleshooting that at the moment.

Kalm_Traveler said:
.... at the moment I'm trying to figure out why my LTE signal suddenly sucks. Odin'ed back to full stock and it still sucked so I am spending most of my free time troubleshooting that at the moment.
Click to expand...
Click to collapse
That sounds a bit reassuring for me. After I flashed this I got a 10mbps decrease in speed. I thought it was just the time of day or something but now I can't ever hit the speeds I had prior to flashing this so I was wondering. It's only 10 mbps but where my house is I don't get the greatest of speeds so any bit counts. I probably won't tell a difference anyway.
I haven't tried restoring to a nandroid yet, I'll keep testing. I don't think it was due to this mod but who knows.

shouren04 said:
That sounds a bit reassuring for me. After I flashed this I got a 10mbps decrease in speed. I thought it was just the time of day or something but now I can't ever hit the speeds I had prior to flashing this so I was wondering. It's only 10 mbps but where my house is I don't get the greatest of speeds so any bit counts. I probably won't tell a difference anyway.
I haven't tried restoring to a nandroid yet, I'll keep testing. I don't think it was due to this mod but who knows.
Click to expand...
Click to collapse
I ended up flashing a nandroid of my EFS partition from 11 days ago and that fixed it. I don't think this mod has anything to do with it because it only changes the CSC code in 3 files there, mps_code.dat , omcnw_code.dat and replace_code.dat all three of those files are just plain text of 3 letters each, on my SK Telecom N950N they were SKC, SKC, and SKO respectively. On my T-Mobile branded Note 5 they are all TMB, so that's what my script set them to.
Also, on this nandroid backup I already had flashed the CSC so I know that isn't the issue. Where I noticed a problem was roughly when I flashed a 950F-based ROM to test out a theory that F-based models came with some files that the N models lacked, which is why my tiny CSC pack enabled T-Mobile wifi calling on F ROMs but not N ROMs.
I am confident that the pack is fine but i am going to work on a new one from scratch specifically for making wifi calling work on the N models, and with a different CSC approach, this pack (and the TEKHD one it spawned from) basically wipe out any existing CSC files and settings, and replace them with it's own. I don't think changing those 3 files on the EFS partition is necessary, nor is having the CSC report that it's from a different model so I am going to build a new pack that simply adds CSC information to the existing data - this way the phone always knows which model it is, and that you are simply using a SIM card and selecting it's matching CSC rather than going with what it was defaulted to. This will work perfectly on the N950N since it was already built with a multi-CSC from the factory, the model info indicates that it is branded for SK Telecom, KT olleh, or LG U+ but none of them are locked, and they all contain the same multi-CSC for all 3 carriers.
Please standby for a few hours while I hammer out this new and improved pack.

Thanks. Another question, for those.of you that installed this, does your LTE indicator next to your reception bars say 4g/LTE or LTE+?

shouren04 said:
Thanks. Another question, for those.of you that installed this, does your LTE indicator next to your reception bars say 4g/LTE or LTE+?
Click to expand...
Click to collapse
the 4g/LTE icon is the T-Mobile icon, if the pack applied properly that is the one you'll get with Download Booster turned off. With it on, the icon should change to an upward-pointing Wifi symbol with LTE above it. The LTE+ icon is from the original CSC.

Kalm_Traveler said:
the 4g/LTE icon is the T-Mobile icon, if the pack applied properly that is the one you'll get with Download Booster turned off. With it on, the icon should change to an upward-pointing Wifi symbol with LTE above it. The LTE+ icon is from the original CSC.
Click to expand...
Click to collapse
Ok, some weird stuff just happened, got it all figured out now....
I have a N950F from Clove UK. The original icons were 4G & 4G+, never saw LTE or LTE+. After I flashed this mod it changed to 4G/LTE like what I'm used to seeing on my TMO N5.
The reason I asked cause I had just changed ro.config.tima from 1 to 0 to get SHealth working again because of root. After doing so I noticed the 4G/LTE indicator changed to LTE+. Also after that build.prop change, the preinstalled Microsoft apps reappeared. After root I wanted to uninstall them but they disappeared, didn't show as installed in Ti Backup either.
But what I didn't notice immediately is that everything I got from installing this mod had disappeared too like as if I never installed it with the exception of the LTE+ icon which I never had before.
Makes sense why the Microsoft apps started working again after the tima change but don't know why it would affect this mod. I simply reflashed this mod & everything's back to normal. Just throwing this out there if it happens to anyone else.

shouren04 said:
Ok, some weird stuff just happened, got it all figured out now....
I have a N950F from Clove UK. The original icons were 4G & 4G+, never saw LTE or LTE+. After I flashed this mod it changed to 4G/LTE like what I'm used to seeing on my TMO N5.
The reason I asked cause I had just changed ro.config.tima from 1 to 0 to get SHealth working again because of root. After doing so I noticed the 4G/LTE indicator changed to LTE+. Also after that build.prop change, the preinstalled Microsoft apps reappeared. After root I wanted to uninstall them but they disappeared, didn't show as installed in Ti Backup either.
But what I didn't notice immediately is that everything I got from installing this mod had disappeared too like as if I never installed it with the exception of the LTE+ icon which I never had before.
I simply reflashed this mod & everything's back to normal. Just tgrowing this out there if it happens to anyone else.
Click to expand...
Click to collapse
is that on the latest version from 9/28? On the first release I noticed that sometimes i had to flash it twice to get it to switch to T-Mobile because it was set to XAA default (I was just copying how the original was set up).

Kalm_Traveler said:
is that on the latest version from 9/28? On the first release I noticed that sometimes i had to flash it twice to get it to switch to T-Mobile because it was set to XAA default (I was just copying how the original was set up).
Click to expand...
Click to collapse
This is on N950FXXU1AQI1 build date 9/1 which I updated from OTA before root. It originally came with N950FXXU1AQH9.
I flashed only once & it worked perefectly fine until today after I changed the tima setting & rebooted. Well twice actually caused I flashed again removing the tmo boot jingle.
My CSC was originally XEU/XEU/XEU when it was on QH9. After the OTA update to QI1 it changed to XEF/XEF/XEU. SIM has always been tmobile since I received it. CSC after flashing this mod is TMB/TMB/XEU.

shouren04 said:
This is on N950FXXU1AQI1 build date 9/1 which I updated from OTA before root. It originally came with N950FXXU1AQH9.
I flashed only once & it worked perefectly fine until today after I changed the tima setting & rebooted. Well twice actually caused I flashed again removing the tmo boot jingle.
My CSC was originally XEU/XEU/XEU when it was on QH9. After the OTA update to QI1 it changed to XEF/XEF/XEU. SIM has always been tmobile since I received it. CSC after flashing this mod is TMB/TMB/XEU.
Click to expand...
Click to collapse
oh I mean when did you download my zip?
Anyhow I am working on a revised one just for adding T-Mobile's features (doesn't contain CSC info for other USA carriers). I noticed that the factory SK Telecom signal bars are deceiving compared to T-Mobile. With LTE Discovery running on my T-Mobile Note 5 right next to SK Telecom Note 8, the Note 5 is typically 7-12 dBm lower (like numerically lower, so on the same band the 5 is -84.0 dBm and the 8 is -97.0 dBm). If I run speed tests side by side the 8 gets a bit quicker downloads for a few minutes but then it suddenly drops. Just now after flashing my new test CSC file, the 5 was getting 50-90mbps down, and the 8 was getting 70-130mbps down, but suddenly the 8 started getting 2-5mbps max.

Kalm_Traveler said:
oh I mean when did you download my zip?
Anyhow I am working on a revised one just for adding T-Mobile's features (doesn't contain CSC info for other USA carriers). I noticed that the factory SK Telecom signal bars are deceiving compared to T-Mobile. With LTE Discovery running on my T-Mobile Note 5 right next to SK Telecom Note 8, the Note 5 is typically 7-12 dBm lower (like numerically lower, so on the same band the 5 is -84.0 dBm and the 8 is -97.0 dBm). If I run speed tests side by side the 8 gets a bit quicker downloads for a few minutes but then it suddenly drops. Just now after flashing my new test CSC file, the 5 was getting 50-90mbps down, and the 8 was getting 70-130mbps down, but suddenly the 8 started getting 2-5mbps max.
Click to expand...
Click to collapse
Oh, I didn't even know there was a revised version. Looks like I have the older one, pack v3a. Still never saw XAA though.
A revised version would be great, I wonder why the need for all the CSCs but I didn't feel like messing with anything. I'll keep an eye out. Thanks

T-Mobile to AT&T

Hi All, I'm trying to make my T-Mobile Note 9 work on AT&T. Using odin I put on the latest ATT version on my phone that I could find -- N960USQU1ARG6. It boots and works fine, but it shows Android 8.1, I don't get wifi calling or there's no place to turn on VOLTE, and when I say update software it says "software up to date." So, I'm assuming that ATT still doesn't think this is their phone.
Any ideas on how to fix this?
Thanks!

Nasty64 said:
Hi All, I'm trying to make my T-Mobile Note 9 work on AT&T. Using odin I put on the latest ATT version on my phone that I could find -- N960USQU1ARG6. It boots and works fine, but it shows Android 8.1, I don't get wifi calling or there's no place to turn on VOLTE, and when I say update software it says "software up to date." So, I'm assuming that ATT still doesn't think this is their phone.
Any ideas on how to fix this?
Thanks!
Click to expand...
Click to collapse
Att has Pie firmware for the Note 9. Just do a search for the newest Pue update and flash it using Odin.

Jammol said:
Att has Pie firmware for the Note 9. Just do a search for the newest Pue update and flash it using Odin.
Click to expand...
Click to collapse
Thanks for the response. That will fix the Wifi calling and VoLTE too?

Nasty64 said:
Thanks for the response. That will fix the Wifi calling and VoLTE too?
Click to expand...
Click to collapse
That I do not know for sure. It doesn't hurt to try though.

Jammol said:
That I do not know for sure. It doesn't hurt to try though.
Click to expand...
Click to collapse
Well, it might. I'd really like to understand what's wrong with it before I flash more.

Nasty64 said:
Well, it might. I'd really like to understand what's wrong with it before I flash more.
Click to expand...
Click to collapse
Well the first thing you could do is do a factory reset, or verify with At&t if it's a feature on your account. Not sure how theirs is setup compared to T-Mobile's Wi-Fi calling. It won't hurt to flash unless you've got stuff you need to backup and have no way to do so.
I don't think anything is wrong with your device. All of the N960U devices are the exact same. The only difference is the software. You don't even need to flash a different firmware for it to put the carrier bloat on the device based on the sim card inserted. It's already included in the Software package on the device, just dormant.

I can't see AT&T Mobility (or any carrier, really) willingly remaining in the trailing position vs. the UnCarrier (who has offered Wi-Fi Calling as a feature (even to their MVNO customers) for over a year - yes, I have had it that long personally) - the only time I don't use it is due to support of the *router* being iffy (some residential routers have issues with Voice over Wi-Fi; the same applies to some business routers).

I went to ATT as well and it took some time for me to see the update to 9. Not sure, when I was with T-Mobile it always showed updates right away. For ATT, I was able to find the ARJA firmware with a CSA7 update that expedited the process. It also took around a day for wifi calling to show up. ATT is just slow to enable things perhaps?

Question VoLTE not working since OneUI 4.0 Beta installation

Hello All,
I posted this in Samsung Community, but unfortunately none was able to help. I am hoping XDA members could help fix this issue.
I am facing a strange problem with my S21 Ultra Unlocked which was directly bought from Samsung. I had enrolled into OneUI 4.0 beta when I was in the US. I was using Sprint connection then.
I had to travel back to my home country (India) and I am using an Airtel sim card (LTE) here. Now, the strange problem is that LTE (data) works here fine. But, VoLTE is not working. The network changes to 2G for phone calls. I am assuming that the auto-switching bands which was introduced in OneUI 4.0 is causing the problem.
Using Smart Switch PC, I rolled back to One UI 3.1. VoLTE and WiFi calling started to work again. But, soon after I got update notification for One UI 4 beta. To confirm that it is indeed an issue with One UI 4, I installed it again. And as expected, I am not getting VoLTE or WiFI calling again.
Since I changed from Sprint to Airtel, I am not able to withdraw from the Beta program as well. I am getting the error "One UI beta features aren't available because your service provider has changed".
Also, I am not sure what the final One UI 4 will offer. For the first time in my life, I am seeing an Android upgrade causing my phone to not able to connect to VoLTE.
I am also attaching the screenshots of Phone Information. As you can see, in OneUI 3.1, VoLTE and WiFi calling are provisioned. But in OneUI 4, both are not available. I am assuming the issue is because IMS is not registered. But, I am not able to find how this can be fixed.
Thanks in advance for your help.
Thanks,
APS
#volte #samsung #s21ultra #oneui #oneui4 #imsservice #ims #airtel #oneuibeta

A quick update - I updated to final version One UI 4 and the issue is still there. I am still not able to get VoLTE or WiFi calling in India.

I am having similar issue. Were you able to figure out anything?

dp1989 said:
I am having similar issue. Were you able to figure out anything?
Click to expand...
Click to collapse
No. I have started a new thread in Samsung US Community. Let's see if it reaches the right team who needs to fix this issue.
Since the issue was previously in the Beta version, I didn't get much support. Now, I can see more people facing the same issue since OneUI 4 final version is out.

Can you please provide Samsung members thread link here (or subject line which will help me find it).. I will reply with same issue

dp1989 said:
Can you please provide Samsung members thread link here (or subject line which will help me find it).. I will reply with same issue
Click to expand...
Click to collapse
Try this "DON'T BUY S21 Series Phones if you want use it outside US".

aps99 said:
Try this "DON'T BUY S21 Series Phones if you want use it outside US".
Click to expand...
Click to collapse
I searched Samsung members app and didn't find any thread like that. May be if you can post a link.

dp1989 said:
I searched Samsung members app and didn't find any thread like that. May be if you can post a link.
Click to expand...
Click to collapse
It's in the US community. Did you search there?

Yes, I searched in US Community.

dp1989 said:
Yes, I searched in US Community.
Click to expand...
Click to collapse
Not sure if URL can be posted here. Let me try anyways.
Samsung account
us.community.samsung.com

Yes. I've noticed this since the beta started, was hoping it would be fixed by the time stable is released, but looks like it isn't.
VoLTE/VoWiFi worked fine in Qatar with One UI 3.1 (US unlocked model) but is unable to activate on One UI 4.
It's a shame, but they probably won't fix it since it still works alright with US sims. Maybe it will be fixed in One UI 5 accidentally next year the same way it broke now, but don't hold your breath.

I would once again rollback to One UI 3.1 and wait for a stable Android 12 One UI 4.0 however it may never work with that device in your region. I won't be updating until they release a better version, still too many bugs. Your best option is sell it and buy your Service Provider's device, that's a permanent fix.

varcor said:
I would once again rollback to One UI 3.1 and wait for a stable Android 12 One UI 4.0 however it may never work with that device in your region. I won't be updating until they release a better version, still too many bugs. Your best option is sell it and buy your Service Provider's device, that's a permanent fix.
Click to expand...
Click to collapse
I am on stable One UI 4.0 now. Still it doesn't work.
I cannot sell a device that has such an issue now that I am in India. I will probably sell it once I am back in US if Samsung doesn't fix this issue before then.

Go to settings -->general> reset ----> reset network settings
And reboot after
Volte shou´d work again

Hey i was having this same problem, but seems to have disappeared since I installed SM-G998U rom. I didn't install Userdata and seems I didn't get any bloatware plus activation is still on. You can try.

SOGKush420 said:
Go to settings -->general> reset ----> reset network settings
And reboot after
Volte shou´d work again
Click to expand...
Click to collapse
That won't work, and is completely irrelevant to the issue at hand. This only applies to the unlocked US model (U1) - the OneUI 4 update misconfigures VoLTE for international SIMs.
U will work, but the branded firmware shouldn't be required, U1 is currently broken.

lui0703 said:
Hey i was having this same problem, but seems to have disappeared since I installed SM-G998U rom. I didn't install Userdata and seems I didn't get any bloatware plus activation is still on. You can try.
Click to expand...
Click to collapse
Did you lose the data? I already factory reset my phone trying to fix this issue, rolling back etc.

aps99 said:
Did you lose the data? I already factory reset my phone trying to fix this issue, rolling back etc.
Click to expand...
Click to collapse
I did a full backup before. And just restored the data via Smart Switch after.

lui0703 said:
I did a full backup before. And just restored the data via Smart Switch after.
Click to expand...
Click to collapse
Just to confirm. Are you having a US phone which is being used outside US? What is your current carrier?

SOGKush420 said:
Go to settings -->general> reset ----> reset network settings
And reboot after
Volte shou´d work again
Click to expand...
Click to collapse
Will you please elaborate the whole procedure how did you installed this rom roll back to one UI 3.1 safely..
I have USA unlocked variant of S21 ultra and i am on stable One UI 4.0. Facing the issues.
..VOLTE AND WIFI CALLING FEATURE NOT WORKING ..
YOUR HELP WOULD BE HIGHLY APPRECIATED

Samsung Galaxy S10 - Unlocked Phone (AT&T Blocked Call Issue)

So many people are reporting with the 3/1 sweep by AT&T, that they are blocking almost all Unlocked phones: See: Downdector Link We personally have a S10 (G973U1). AT&T is saying on this list: AT&T approved phone list that it is supposed to work. But like many other people "calls" end immediately, but we can text and data work. It is some sorta ploy by AT&T to force us to upgrade our phones. They want us all to upgrade to S22s. Anyway I was ranting. Anyway, if you look at that link, they are saying that the phone has to be on the latest software. The last update from AT&T or the manufacturer was in January. I checked the firmware site, and Android 11 is the latest in January. I'm wondering if there is some hack to get us on to '12' or something. An update might solve this issue. We know that a new SIM does not work. Calls seem to be rejected on the network, just based on the phone model or Android version.
We are aware that a version 12 is out there for the phone, just that firmware is not for our US-unlocked model yet. But maybe it can be hacked?
Edit: It appears this thread may be linked with this older one... But it is ever more pressing issue now:
S10 Unlocked phone with AT&T Firmware here they explain how, and the problems with flashing. This was back in 2019, so I'm not sure if this will still work. Even then it didn't work for everyone. Some in that forum claimed that it did. AT&T seems to now be blocking from their calling network any phones not enabled with VOLTE and the extended AT&T services that are not present in Unlocked phones.

robertkjr3d said:
So many people are reporting with the 3/1 sweep by AT&T, that they are blocking almost all Unlocked phones: See: Downdector Link We personally have a S10 (G973U1). AT&T is saying on this list: AT&T approved phone list that it is supposed to work. But like many other people "calls" end immediately, but we can text and data work. It is some sorta ploy by AT&T to force us to upgrade our phones. They want us all to upgrade to S22s. Anyway I was ranting. Anyway, if you look at that link, they are saying that the phone has to be on the latest software. The last update from AT&T or the manufacturer was in January. I checked the firmware site, and Android 11 is the latest in January. I'm wondering if there is some hack to get us on to '12' or something. An update might solve this issue. We know that a new SIM does not work. Calls seem to be rejected on the network, just based on the phone model or Android version.
We are aware that a version 12 is out there for the phone, just that firmware is not for our US-unlocked model yet. But maybe it can be hacked?
Edit: It appears this thread may be linked with this older one... But it is ever more pressing issue now:
S10 Unlocked phone with AT&T Firmware here they explain how, and the problems with flashing. This was back in 2019, so I'm not sure if this will still work. Even then it didn't work for everyone. Some in that forum claimed that it did. AT&T seems to now be blocking from their calling network any phones not enabled with VOLTE and the extended AT&T services that are not present in Unlocked phones.
Click to expand...
Click to collapse
I was helped by a user to achieve ascendance onto the AT&T network. I'm not sure if I'm to reveal his name. We 1) go into Developers mode on the phone. 2) Hack the Kernel. 3) Flash the rom to the G973U (model)... with the AT&T firmware. So that the Wifi-Calling and 5G features would work, and AT&T would allow it on their network.

robertkjr3d said:
I was helped by a user to achieve ascendance onto the AT&T network. I'm not sure if I'm to reveal his name. We 1) go into Developers mode on the phone. 2) Hack the Kernel. 3) Flash the rom to the G973U (model)... with the AT&T firmware. So that the Wifi-Calling and 5G features would work, and AT&T would allow it on their network.
Click to expand...
Click to collapse
I've literally been searching for an answer to this for days now. My wife and I have S10's. I work far from home so I really need her phone working in case of emergency. Can you please point me in the general direction? Thanks!

Agreed, I didn't know such a thing was possible, but I'd love to hear more about this!

skrapmetal said:
I've literally been searching for an answer to this for days now. My wife and I have S10's. I work far from home so I really need her phone working in case of emergency. Can you please point me in the general direction? Thanks!
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At first I had to use the Samsung Band Selector app from the Play store and go into More Network Settings > AT&T > Preferred Network Type and choose 3G. Unfortunately this killed LTE so all data and calls were going through H+. As I was mostly on wifi I could live with it since I could actually use the phone again.
Then Friday morning I checked for updates and there was the update to take me to Android 12. I took the update then when it finished it said it needed to reboot to connect new SIM to carrier services....it wasn't a new SIM. I let it reboot and everything was working with VoLTE again.
Hope this helps.

KennyG123 said:
At first I had to use the Samsung Band Selector app from the Play store and go into More Network Settings > AT&T > Preferred Network Type and choose 3G. Unfortunately this killed LTE so all data and calls were going through H+. As I was mostly on wifi I could live with it since I could actually use the phone again.
Then Friday morning I checked for updates and there was the update to take me to Android 12. I took the update then when it finished it said it needed to reboot to connect new SIM to carrier services....it wasn't a new SIM. I let it reboot and everything was working with VoLTE again.
Hope this helps.
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I appreciate you getting back to me. Unfortunately I am still on android 11 with a custom ROM and also this is a global phone so that app didnt work for me. I dont receive OTA updatez. I'll update to a new ROM and see what happens. Thanks

Question Is the signal band set the same for SM-G998U and SM-G998U1?

Greetings to the community here!
I came here out of desperation because after several attempts I can't fix the problem with my phone.
I have a Samsung Galaxy S21 Ultra, specifically the model SM-G998U (CSC: ATT/XAA,ATT/ATT). The phone is unlocked and accepts all SIM cards. I live in the Czech Republic (the state in the center of Europe) and I found out that my signal is dropping here. A cell phone imported from the US has different radio waves. See the comparison there:
https://www.kimovil.com/en/frequency-checker/CZ/samsung-galaxy-s21-ultra
I wanted to ask if it is possible to solve this error by flashing SM-998U into SM-998U1 + before flashing, changing the CSC to XAA (or is it after flashing?). The phone has Android 12 and the last update was on April 1, 2022. However, I can't update anything because thanks to AT&T I have to be in the US + have their SIM to be able to get the OTA. Could mobile signal be a software issue (like if I manage to update it, is it going to accept European bands – certainly O2 carrier?)? It keeps losing signal (it switches between no signal - LTE - 5G). During the call, the other party can't hear me because my voice somehow falls out.
By the way, the seller told me that the phone will work in Europe, but it doesn't work for me to make calls. Do I have the right to return the goods?
Is there any kind soul who can help me with this? I will be grateful for any help.

UnknownColour said:
Greetings to the community here!
I came here out of desperation because after several attempts I can't fix the problem with my phone.
I have a Samsung Galaxy S21 Ultra, specifically the model SM-G998U (CSC: ATT/XAA,ATT/ATT). The phone is unlocked and accepts all SIM cards. I live in the Czech Republic (the state in the center of Europe) and I found out that my signal is dropping here. A cell phone imported from the US has different radio waves. See the comparison there:
https://www.kimovil.com/en/frequency-checker/CZ/samsung-galaxy-s21-ultra
I wanted to ask if it is possible to solve this error by flashing SM-998U into SM-998U1 + before flashing, changing the CSC to XAA (or is it after flashing?). The phone has Android 12 and the last update was on April 1, 2022. However, I can't update anything because thanks to AT&T I have to be in the US + have their SIM to be able to get the OTA. Could mobile signal be a software issue (like if I manage to update it, is it going to accept European bands – certainly O2 carrier?)? It keeps losing signal (it switches between no signal - LTE - 5G). During the call, the other party can't hear me because my voice somehow falls out.
By the way, the seller told me that the phone will work in Europe, but it doesn't work for me to make calls. Do I have the right to return the goods?
Is there any kind soul who can help me with this? I will be grateful for any help.
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Yes you are right . Facing the same problem here in Pakistan I have G998U model and it drop the signal from 4g to 3g (H+) frequently . I use the phone Hotspot in my car to listen to music . But on the same route it drops the signals and keep buffering. In Pakistan Samsung officially released G998B model but I don't like the exynos chip

jahanzaiblohani said:
Yes you are right . Facing the same problem here in Pakistan I have G998U model and it drop the signal from 4g to 3g (H+) frequently . I use the phone Hotspot in my car to listen to music . But on the same route it drops the signals and keep buffering. In Pakistan Samsung officially released G998B model but I don't like the exynos chip
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Thanks for responding.
I noticed you flashed from SM-G998U to SM-G998U1. Did you notice any change in the signal when you flashed the system? Like, is it better after flashing?
I'm thinking of flashing from the G998U to the G998U1 as well.
Now I have CSC ATT. When I flash it to G998U1 do I have to change the CSC to XAA (via SamFW tool) or just flash it via patched ODIN?
Also, I don't want to lose data when flashing, so I have to put HOME_CSC in the patched ODIN right? I just don't know if putting HOME_CSC will leave the AT&T logo and bloatware on my phone. I don't want to be left with AT&T bloatware, so I'll probably backup my data and put a normal CSC in there that will wipe my data.

@iBowToAndroid
Would you mind helping me out, please? Someone on this page wrote that I should be careful about the bootloader version when flashing. Can I flash from Android 12 (April 2022) to Android 13?

UnknownColour said:
@iBowToAndroid
Can I flash from Android 12 (April 2022) to Android 13?
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Of course