Question Problem - 3G During Phone Calls - Samsung Galaxy S23 Ultra

History:
Recently purchased a S23 Ultra (SM-S918U1) from Samsung USA. Downloaded and flashed the appropriate software for Samsung Canada (SM-S918W) using Patched Odin (3.14.1_3B). CSC, as expected, now reads TLS/TLS,TLS/XAA.
Network mode is set to 5G/LTE/WCDMA/GSM.
Problem:
I have strong signal in my area, 5G, but during phone calls, my signal drops from 5G to 3G (WCDMA) as opposed to the expected LTE+/LTE (4G or 4G+ for anyone outside of North America).
I have changed to a new SIM card and am able to reproduce the issue on my S22 Ultra.
I'm beginning to think it is a carrier issue, Telus, and have escalated to appropriate support tier for a callback.
Is anything else I should be looking for in-between? Specific flashing techniques or tools?
Thanks!

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if you dont have VoLTE enabled then your signal goes to 3g during phone calls, its how the network works.

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Aleks95 said:
if you dont have VoLTE enabled then your signal goes to 3g during phone calls, its how the network works.
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I greatly appreciate your help! I knew it would be something simple.
Enabling VoLTE is no longer available with this Canadian CSC (Telus/TLS).
I tested two devices; my S22 Ultra and Z Flip 4; the Z Flip 4 was purchased directly from Telus Canada, while the S22 Ultra was purchased from Samsung USA.
Following a factory reset and reboot, the Z Flip 4 automatically registers for IMS/VoLTE.
The same cannot be said for the S22 Ultra when running TLS. I see an option to enable 'VoLTE' if I switch back to XAA from XAC, but it doesn't do anything.
It appears the carrier may blacklist non-Telus purchased devices based on specific criteria (e.g., IMEI, serial number, etc).
This was not the case before 2021.

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It is a carrier issue. Bell/Telus blocking VoLTE and WiFi Calling on non-Canadian devices that are not sold by Bell/Telus. If you put a Rogers SIM in your device, everything will work because Rogers is not limiting devices by IMEI and model number where Bell/Telus are!
File a CCTS complaint. The more they get. The hope that something will be done about it. They will also block your device from roaming on to US carriers and block 911 access as well. I get a text every month from Telus saying, "
TELUS Message: Hi J********, as you may be aware, carriers in the U.S. stopped supporting mobile devices on 3G networks.
You’re currently using a 3G phone that connects to 3G networks and the next time you roam in the U.S., you will no longer be able to use data, text or make phone calls - including 911.
To stay connected in the U.S., you need to replace your phone with an LTE or 5G capable phone.
Learn more about the 3G network turndown in the U.S. at https://sms.telus.com/a519646aed"
I purchased mine from T-Mobile USA and use it with my T-Mobile SIM and Telus eSIM. I am on the U1 firmware.

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Just call the Telus, telling them you brought a S23u from Samsung Canada. The model is S23 Ultra or SM-S918W. They will "apply the IMS registration profile" to enable the VoLTE and WifiCalling. That's how I did on my S918B. You don't need to change the CSC at all.

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Thank you all for your excellent responses. I appreciate your help.
Telus' advanced support confirmed that non-Canadian Samsung devices are being blocked
Telus requests IMEIs from Samsung and registers IMS (VoLTE/WiFi Calling) if it matches the corresponding devices.
Google and Apple are the only exceptions. These criteria do not apply to them.
The next stop for me is the CRTC. If this concerns you as a resident of Canada, more information can be found here:
How to Make a Complaint About Your Telephone Service | CRTC
Telephone service problems can be resolved by making a complaint to the phone company, CCTS or CRTC.
crtc.gc.ca

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and2cs said:
Just call the Telus, telling them you brought a S23u from Samsung Canada. The model is S23 Ultra or SM-S918W. They will "apply the IMS registration profile" to enable the VoLTE and WifiCalling. That's how I did on my S918B. You don't need to change the CSC at all.
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Click to collapse
This is actually what I was planning to do but before I could ask, they, the Telus Rep., had already identified it as non-Telus device.

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AHE_XDA said:
Thank you all for your excellent responses. I appreciate your help.
Telus' advanced support confirmed that non-Canadian Samsung devices are being blocked
Telus requests IMEIs from Samsung and registers IMS (VoLTE/WiFi Calling) if it matches the corresponding devices.
Google and Apple are the only exceptions. These criteria do not apply to them.
The next stop for me is the CRTC. If this concerns you as a resident of Canada, more information can be found here:
How to Make a Complaint About Your Telephone Service | CRTC
Telephone service problems can be resolved by making a complaint to the phone company, CCTS or CRTC.
crtc.gc.ca
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Click to collapse
CRTC won't do anything, neither will CCTS. They claim networks can do this for the "safety" of their network. Only Rogers allows US devices to use VoLTE for some reason.
I went through this last year.

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and2cs said:
Just call the Telus, telling them you brought a S23u from Samsung Canada. The model is S23 Ultra or SM-S918W. They will "apply the IMS registration profile" to enable the VoLTE and WifiCalling. That's how I did on my S918B. You don't need to change the CSC at all.
Click to expand...
Click to collapse
Won't last sorry. If your IMEI isn't on the whitelist it will be eventually kicked off the profile.