[Samsung Galaxy Note 20 Ultra Guides, News, & Discu] warriorvibhu:
Quick Note before you start this - If you are on stable one UI 3.x / Android 11 or greater, see the bottom of the post to see the workaround. Thanks to @knuschit

Introduction - If you have ever bought a device that comes locked with the carrier you will see there are some carrier baked features missing in unlocked devices. While putting in your sim will change CSC of your device you might still not get all the features. So far i fail to understand why would device makers and Carriers make it so difficult for users. I have scourged through so many forums and found info like these where a t-mobile rep responds saying there is no way those features can be added to non carrier branded device ( Either a blatant lie or the reps are ill informed or both).

My Device - Unlocked SM-N986U1 with tmobile sim - CSC - TMB/TMB/XAA

Problem Statement- I want Video calling over LTE and RCS features.

Solution - Follow the steps carefully and also see the attached screenshots -

There are other ways of doing this by creating shortcut to ims service settings but i am posting something that most users can easily do.

Quick Pre-Check - Before starting if you have been using RCS on Google Messages you might want to de-register. Follow the process here: https://messages.google.com/disable-chat.

You can always activate it in case you want to go back to RCS on google messages.

This will only work if you are on Android 10, or the Beta version of Android 11. Samsung has blocked this on Stable Android 11.

STEPS​

1. Download and install Phone app (By google)

2. Open the phone App that you just downloaded and make it your default Phone app.

3. Dial *#*#467#*#*

4. You will see the settings as in my Screenshot 1

5. Tap on IMS Service Switch (The first Option)

6. See the Screenshot 2 and move all the switches to ON.

7. Go back to main page and then go to RCS Configuration settings and make sure they are selected to be always on as in Screenshot 3.

8. I changed back to default phone app after this.

9. And done you should have the video calling over LTE to fellow T-Mobile users activated now.

I have already made a few calls and tested it and can confirm that this works. This might work for Sprint too.

NOTE THAT - Default video call on contacts is still duo. you have to make a regular voice call to a contact first then you will see the native video call icon.

These settings wont stick after OS/Firmware update via Odin, OTA or Sideload and steps would need to be repeated.​

Edit Update -You can See all three screenshots together here.

Let us know how it goes here and if you explored any more settings and i will update this post with due credit.

WORKAROUND

: SINCE THE ABOVE METHOD IS NOT WORKING ON

ONE UI 3.X / Android 11

​

The conventional method doesnt work on Android 11 so use the method below:

1. Install Alliance Shield X >> Create account and Give necessary permissions

2. Open Alliance Shield X settings and toggle New App Manager Layout On

3. Look at this post and follow

4. See the Screenshot 2 and move all the switches to ON.

5. Go back to main page and then go to RCS Configuration settings and make sure they are selected to be always on as in Screenshot 3.

I can confirm this works.

ADDITIONAL CONFIRMED INFO FROM USERS / TROUBLESHOOTING​

Try the following step in case you had RCS activated on Google Messages and doing the above steps does not get you RCS in the Native SMS App. Thanks @Compusmurf

Confirmed to be working for ATT

It works for other phones too