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US users operating a G930F (Exynos) on T mobile in the US.

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Ritor

Member
Dec 18, 2017
31
4
Samsung Galaxy S5
I'm using a G930F with stock ROM, on Tmobile, and the January '21 update.

I'm using the UK BTU CSC. Been using this phone since 2018,; the first two years it worked fine, didn't get this error. Tmobile says my SIM card isn't the issue, and their tech support just has me do standard stuff like wiping data etc. Same issue even if I do a full factory reset.

I've noticed sometime nearly a year ago, my G930F started giving me a "Not registered on network" error msg when I tried to make a call, and SMS texts wouldn't go through, but internet was fine.

Toggling airplane mode on/off temporarily fixes this. (the phone will eventually log off so that I have to redo the airplane mode toggle or reboot.

Does anyone know what the issue is?

Is it just only certain G930F users that experience this on tmobile in the US, or is it all users?

Thanks.
 

Feenix0

Senior Member
I'm having a similar problem on AT&T. I also use a G930F (exynos) S7. Mine is rooted and flashed with LightROM, which is based on stock firmware. CSC is OXM/XEU. As you may know, AT&T is phasing out 3G, and my phone can't make calls in LTE only mode. I've been on chat with their customer service for an hour, and they have no idea why it isn't working. Can someone explain what I need to do to get this phone working?

It's an international version phone, so I wonder if the CSC is incompatible with AT&T. I understand that it is possible (in some cases) to change the CSC code, but I don't know how. The only methods I've found required me to install a stock USA firmware, but I haven't been able to find one. I think I'd need the ATT, XAA, or XAS firmware, but I'm not even sure that the CSC is the problem. But I'd expect the phone's VoLTE/HD voice capabilities to work because it has the stock drivers from Samsung in this ROM.
 

Droiderat

Senior Member
Nov 3, 2013
266
108
I'm using a G930F with stock ROM, on Tmobile, and the January '21 update.

I'm using the UK BTU CSC. Been using this phone since 2018,; the first two years it worked fine, didn't get this error. Tmobile says my SIM card isn't the issue, and their tech support just has me do standard stuff like wiping data etc. Same issue even if I do a full factory reset.

I've noticed sometime nearly a year ago, my G930F started giving me a "Not registered on network" error msg when I tried to make a call, and SMS texts wouldn't go through, but internet was fine.

Toggling airplane mode on/off temporarily fixes this. (the phone will eventually log off so that I have to redo the airplane mode toggle or reboot.

Does anyone know what the issue is?

Is it just only certain G930F users that experience this on tmobile in the US, or is it all users?

Thanks.
Your problem is a consequence of the T-Mo acquisition of Sprint, and the resulting network reconfiguration which occurred in early 2021. The legacy Sprint bands (25, 26 and 41) do not support voice calls when connected to LTE; when connected to one of these bands, you must use VoLTE (which is different from LTE-Voice). And, therefore, when connected to one of the these bands, you will see "Not registered on network", although data will still work.

You can verify which bands you are connecting to by using the apps LTE Discovery or Signal Spy.

The solution is to enable the SM-G930F to use VoLTE.

-- Backup the data on your phone (you will lose it)
-- Download the Windows software "Samfirm", and then use it to download the official Samsung ROM for "EVR", and install it using Odin.
-- Install TWRP (I use twrp-3.5.2_9-MoRo-1.6-herolte)
-- I suggest following that by immediately installing the Alexndr ROM: https://forum.xda-developers.com/t/...vbase-v7-4-encryption-support-jul-10.3592914/ This is a debloated version of the official ROM, so everything works properly. Be sure to follow the instructions for keeping your CSC (in this case, EVR). Root the phone using Magisk.
-- I suggest using the ThundeRStormS kernel, which is MUCH more stable than the kernel in the Alexndr ROM (the stock kernel reboots randomly; the TS kernel does not).
-- Reinstall your data; reconfigure phone.
-- Download the app IMS Settings to enable VoLTE (you will need to re-implement these settings whenever you reboot).

You will find after doing this that VoLTE (and T-Mo or, in my case, Mint) works perfectly, and you will be able to connect to all of the bands now supported by T-Mo and the SM-G930F without issue.
 
Last edited:
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Feenix0

Senior Member
Your problem is a consequence of the T-Mo acquisition of Sprint, and the resulting network reconfiguration which occurred in early 2021. The legacy Sprint bands (25, 26 and 41) do not support voice calls when connected to LTE;; when connected to one of these bands, you must use VoLTE (which is different from LTE-Voice). And, therefore, when connected to one of the these bands, you will see "Not registered on network", although data will still work.

You can verify which bands you are connecting to by using the apps LTE Discovery or Signal Spy.

The solution is to enable the SM-G930F to use VoLTE.

-- Backup the data on your phone (you will lose it)
-- Download the Windows software "Sanfirm", and then use it download the official Samsung ROM for "EVR", and install it using Odin.
-- Install TWRP (I use twrp-3.5.2_9-MoRo-1.6-herolte)
-- I suggest following that by immediately installing the Alexndr ROM: https://forum.xda-developers.com/t/...vbase-v7-4-encryption-support-jul-10.3592914/ This is a debloated version of the official ROM, so everything works properly. Be sure to follow the instructions for keeping your CSC (in this case, EVR). Root the phone using Magisk.
-- I suggest using the ThuneRStorM kernel, which is MUCH more stable than the kernel in the Alexndr ROM (the stock kernel reboots randomly; the TS kernel does not).
-- Reinstall your data; reconfigure phone.
-- Download the app IMS Settings to enable VoLTE (you will need to re-implement these settings whenever you reboot).

You will find after doing this that VoLTE (and T-Mo or, in my case, Mint) works perfectly, and you will be able to connect to all of the bands now supported by T-Mo and the SM-G930F without issue.
Will these instructions work for AT&T also? What is the correct site for downloading SamFirm?
 
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Feenix0

Senior Member
They likely will (but I don't use AT&T, so I can't confirm). It is SanFirm, not SamFirm. Google is your friend.
Thanks! Actually, duckduckgo is my friend ;), but I only saw results for SamFirm, but there were several different ones and I don't want to use a copycat site that may have tampered with something. I think I'm safer trusting info I get on xda.
 

Droiderat

Senior Member
Nov 3, 2013
266
108
Thanks! Actually, duckduckgo is my friend ;), but I only saw results for SamFirm, but there were several different ones and I don't want to use a copycat site that may have tampered with something. I think I'm safer trusting info I get on xda.
DuckDuckGo uses the Microsoft Bing search engine. My version of SamFirm is 0.3.7.1. I don't know which site I got it from.

When I open my SamFirm app, there is now a notice which tells me there is a newer version of the software, called SamUpdate.. See https://kfhost.net/firmware/samupdate I haven't yet tried the new download method, as the SamFirm tool still works.
 
Last edited:
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Ritor

Member
Dec 18, 2017
31
4
Samsung Galaxy S5
Your problem is a consequence of the T-Mo acquisition of Sprint, and the resulting network reconfiguration which occurred in early 2021. The legacy Sprint bands (25, 26 and 41) do not support voice calls when connected to LTE;; when connected to one of these bands, you must use VoLTE (which is different from LTE-Voice). And, therefore, when connected to one of the these bands, you will see "Not registered on network", although data will still work.

You can verify which bands you are connecting to by using the apps LTE Discovery or Signal Spy.

The solution is to enable the SM-G930F to use VoLTE.

-- Backup the data on your phone (you will lose it)
-- Download the Windows software "Sanfirm", and then use it download the official Samsung ROM for "EVR", and install it using Odin.
-- Install TWRP (I use twrp-3.5.2_9-MoRo-1.6-herolte)
-- I suggest following that by immediately installing the Alexndr ROM: https://forum.xda-developers.com/t/...vbase-v7-4-encryption-support-jul-10.3592914/ This is a debloated version of the official ROM, so everything works properly. Be sure to follow the instructions for keeping your CSC (in this case, EVR). Root the phone using Magisk.
-- I suggest using the ThuneRStorM kernel, which is MUCH more stable than the kernel in the Alexndr ROM (the stock kernel reboots randomly; the TS kernel does not).
-- Reinstall your data; reconfigure phone.
-- Download the app IMS Settings to enable VoLTE (you will need to re-implement these settings whenever you reboot).

You will find after doing this that VoLTE (and T-Mo or, in my case, Mint) works perfectly, and you will be able to connect to all of the bands now supported by T-Mo and the SM-G930F without issue.
Thanks for the thorough response! I actually used to use the EVR csc in years prior, but switched to BTU due to the EVR bloatware. Does it really make a difference ?
 

Droiderat

Senior Member
Nov 3, 2013
266
108
Thanks for the thorough response! I actually used to use the EVR csc in years prior, but switched to BTU due to the EVR bloatware. Does it really make a difference ?
I don't actually know. I researched VoLTE, and the suggestion I found was to use EVR. I didn't try using the IMS Settings app with BTU (my original CSC). I am not aware of any bloatware in EVR, but I immediately overwrote EVR with the Alexndr ROM, retaining only the EVR CSC. So, if EVR had bloatware, I wouldn't know.

I recorded the steps I followed, and I can attest that it works. There may be other solutions.
 

Ritor

Member
Dec 18, 2017
31
4
Samsung Galaxy S5
I don't actually know. I researched VoLTE, and the suggestion I found was to use EVR. I didn't try using the IMS Settings app with BTU (my original CSC). I am not aware of any bloatware in EVR, but I immediately overwrote EVR with the Alexndr ROM, retaining only the EVR CSC. So, if EVR had bloatware, I wouldn't know.

I recorded the steps I followed, and I can attest that it works. There may be other solutions.
I understand. When I originally bought my G930F, it had a latin american CSC. I first tried EVR from SamMobile, and it came with a bunch of uk carrier specific bloatware. I later installed BTU after reading it was the generic UK csc for non carrier branded phones.
 

Feenix0

Senior Member
Finally digging into this process now that I have a temp phone.

After Odin failing to flash with either the BTU and EVR, I started writing this post and took a picture of the download mode screen. Contrary to everything I saw in my phone's status and information apps, the download screen showed:

PRODUCT NAME: SM-G930W8

I guess it's no wonder it didn't work!!!!! I'm just glad the flashing TWRP and LightROM for the wrong model didn't ruin my device.

Edit: Turns out that the hardware in these two models is the same, so no surprise it didn't cause trouble.
 
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    I'm using a G930F with stock ROM, on Tmobile, and the January '21 update.

    I'm using the UK BTU CSC. Been using this phone since 2018,; the first two years it worked fine, didn't get this error. Tmobile says my SIM card isn't the issue, and their tech support just has me do standard stuff like wiping data etc. Same issue even if I do a full factory reset.

    I've noticed sometime nearly a year ago, my G930F started giving me a "Not registered on network" error msg when I tried to make a call, and SMS texts wouldn't go through, but internet was fine.

    Toggling airplane mode on/off temporarily fixes this. (the phone will eventually log off so that I have to redo the airplane mode toggle or reboot.

    Does anyone know what the issue is?

    Is it just only certain G930F users that experience this on tmobile in the US, or is it all users?

    Thanks.
    Your problem is a consequence of the T-Mo acquisition of Sprint, and the resulting network reconfiguration which occurred in early 2021. The legacy Sprint bands (25, 26 and 41) do not support voice calls when connected to LTE; when connected to one of these bands, you must use VoLTE (which is different from LTE-Voice). And, therefore, when connected to one of the these bands, you will see "Not registered on network", although data will still work.

    You can verify which bands you are connecting to by using the apps LTE Discovery or Signal Spy.

    The solution is to enable the SM-G930F to use VoLTE.

    -- Backup the data on your phone (you will lose it)
    -- Download the Windows software "Samfirm", and then use it to download the official Samsung ROM for "EVR", and install it using Odin.
    -- Install TWRP (I use twrp-3.5.2_9-MoRo-1.6-herolte)
    -- I suggest following that by immediately installing the Alexndr ROM: https://forum.xda-developers.com/t/...vbase-v7-4-encryption-support-jul-10.3592914/ This is a debloated version of the official ROM, so everything works properly. Be sure to follow the instructions for keeping your CSC (in this case, EVR). Root the phone using Magisk.
    -- I suggest using the ThundeRStormS kernel, which is MUCH more stable than the kernel in the Alexndr ROM (the stock kernel reboots randomly; the TS kernel does not).
    -- Reinstall your data; reconfigure phone.
    -- Download the app IMS Settings to enable VoLTE (you will need to re-implement these settings whenever you reboot).

    You will find after doing this that VoLTE (and T-Mo or, in my case, Mint) works perfectly, and you will be able to connect to all of the bands now supported by T-Mo and the SM-G930F without issue.
    1
    Thanks! Actually, duckduckgo is my friend ;), but I only saw results for SamFirm, but there were several different ones and I don't want to use a copycat site that may have tampered with something. I think I'm safer trusting info I get on xda.
    DuckDuckGo uses the Microsoft Bing search engine. My version of SamFirm is 0.3.7.1. I don't know which site I got it from.

    When I open my SamFirm app, there is now a notice which tells me there is a newer version of the software, called SamUpdate.. See https://kfhost.net/firmware/samupdate I haven't yet tried the new download method, as the SamFirm tool still works.