No VoLTE / 5G / WiFi Calling on AT&T with Unlocked Model...

Been getting strange timeouts over ATT data on the S20Ultra like maybe when scrolling though Youtube comments the circle will just spin and not load the comments - switching to wi-fi instantly starts loading. Wonder if this is just a fault of the new phone or just general network problems in my area. Never had this happen with my S10.

This has recently started happening to me as well. Then I pop my sim in my ATT branded Note 10+ and no issues at all. Such a frustrating experience using unlocked devices on ATT other than the iPhone. Already thinking about returning for a S20+ due to the camera issues. Was hoping to go unlocked with the S20+ but almost afraid to at this point.
 
I don't use WiFi calling and not sure about VoLTE, but are you saying there will be no use of 5G on AT&T with an unlocked phone? Even with an AT&T unlimited plan with 5G?

If I didn't have wifi Calling.
I couldn't use my phone at home, and a lot of places I go.
 
This has recently started happening to me as well. Then I pop my sim in my ATT branded Note 10+ and no issues at all. Such a frustrating experience using unlocked devices on ATT other than the iPhone. Already thinking about returning for a S20+ due to the camera issues. Was hoping to go unlocked with the S20+ but almost afraid to at this point.

I wonder if we should call AT&T and Samsung to let them know that there is a networking performance problem so that they can fix it?
 
Yes, could be a software fix could solve

I have a feeling this maybe the case. I have noticed that when I unlock my phone from sleep it says LTE+ and quickly switches to LTE before unlocking. One would expect just the opposite would happen where the device would not use carrier aggregation during sleep, and then start using carrier aggregation when you start utilizing the device. Of course this could just be false reporting where the LTE+ icon is temporarily incorrectly displayed I suppose, but it is really weird when it happens.

I'm particularly frustrated because my iPhone 11 Pro Max is producing more consistent speed results and higher upload results, while actual signal quality appears to be better on the S20. The other weird thing that has been happening to me involves group messaging with iPhone users. After I have removed my phone number from iMessage, I could text back and fourth with iPhone users without issue. However when an iPhone user sends a group message to me and other iPhone users, I get a MMS from the sender with no indication that the message is a group message. Interestingly, a download button appears to download the MMS even though over MMS messages are auto downloaded in the Samsung messaging app, and it says "No message". Hit download and it just spins and does nothing. Very frustrating to the point I stuck my SIM back into my 11 Pro Max until I can find a solution.
 
I have a feeling this maybe the case. I have noticed that when I unlock my phone from sleep it says LTE+ and quickly switches to LTE before unlocking. One would expect just the opposite would happen where the device would not use carrier aggregation during sleep, and then start using carrier aggregation when you start utilizing the device. Of course this could just be false reporting where the LTE+ icon is temporarily incorrectly displayed I suppose, but it is really weird when it happens.

I'm particularly frustrated because my iPhone 11 Pro Max is producing more consistent speed results and higher upload results, while actual signal quality appears to be better on the S20. The other weird thing that has been happening to me involves group messaging with iPhone users. After I have removed my phone number from iMessage, I could text back and fourth with iPhone users without issue. However when an iPhone user sends a group message to me and other iPhone users, I get a MMS from the sender with no indication that the message is a group message. Interestingly, a download button appears to download the MMS even though over MMS messages are auto downloaded in the Samsung messaging app, and it says "No message". Hit download and it just spins and does nothing. Very frustrating to the point I stuck my SIM back into my 11 Pro Max until I can find a solution.

Arrrgggg, I HATE iMessage and Apple should be forced to allow it to work with Text messages and allow 3rd party Apps to Forward from iMessage to Texts messages on Android phones
 
Unlocked 512 GB Ultra with my old ATT SIM installed yesterday. No VoLTE, 5G indication/WiFi Calling on mine, too.

I called ATT to update the IMEI, which took forever. After it was supposedly all done, I received an email that the tech had restarted my plan effective today's date; and this raised the monthly cost

After 30 minutes on hold for a second tech, I was assured that the email was computer generated; and my plan had not been changed.

I guess I'll see what I shall see.

Still no VoLTE showing up in the Settings.
 
Unlocked 512 GB Ultra with my old ATT SIM installed yesterday. No VoLTE, 5G indication/WiFi Calling on mine, too.

I called ATT to update the IMEI, which took forever. After it was supposedly all done, I received an email that the tech had restarted my plan effective today's date; and this raised the monthly cost

After 30 minutes on hold for a second tech, I was assured that the email was computer generated; and my plan had not been changed.

I guess I'll see what I shall see.

Still no VoLTE showing up in the Settings.

Why should it raise the monthly cost.
If all 5G is about is raising the prices .

Stop 5G.

They say 5 G is the future.



Who's gonna pay for it.
Not me.
When they went from 3G to 4G did they go up on charges
 
Unlocked 512 GB Ultra with my old ATT SIM installed yesterday. No VoLTE, 5G indication/WiFi Calling on mine, too.

I called ATT to update the IMEI, which took forever. After it was supposedly all done, I received an email that the tech had restarted my plan effective today's date; and this raised the monthly cost

After 30 minutes on hold for a second tech, I was assured that the email was computer generated; and my plan had not been changed.

I guess I'll see what I shall see.

Still no VoLTE showing up in the Settings.

Try making a call while on LTE and see if it stays on LTE. That is the only way you will see if it is working. I have the unlocked Ultra on AT&T and VOLTE works. I don't have 5G where I am so I do not know if it works. Wifi calling does not work, but I never use it anyway. My data plan has not changed.
 
Unlocked 512 GB Ultra with my old ATT SIM installed yesterday. No VoLTE, 5G indication/WiFi Calling on mine, too.

I called ATT to update the IMEI, which took forever. After it was supposedly all done, I received an email that the tech had restarted my plan effective today's date; and this raised the monthly cost

After 30 minutes on hold for a second tech, I was assured that the email was computer generated; and my plan had not been changed.

I guess I'll see what I shall see.

Still no VoLTE showing up in the Settings.

So, after you updated the imei...can you confirm that you did get 5G or even 5Ge