Can share how to enable volte for m1 and tpg?
Sent from Samsung SM-G973F using GAGT
Sure.
I suggest you do whatever system updates you want first as those will undo the VoLTE "fix" though (I had to redo it after updating to 9.5.7).

EDIT: HIGHLY RECOMMENDED THAT YOU DO A NANDROID BACKUP USING TWRP OR WHATEVER BEFORE DOING THIS JUST IN CASE YOU !@#% SOMETHING UP.
- Go to your dialer and enter *#800#
- Click enter > oneplus logkit -> function switch -> enable volte switch and vowifi switch
- If you don't see those checkboxes, update the Logkit using the APK from
https://forum.xda-developers.com/showpost.php?p=79577939&postcount=23 and do the above steps.
You need a PC for this part. Go to
https://forum.xda-developers.com/oneplus-7-pro/help/force-enable-volte-vowifi-t3934227 and follow the instructions. But basically..
- Download and install the linked QPST thing then download and install the driver.
- Go to the dialer and enter *#801#. Turn on Serial and Full-Port.
- Connect phone to PC.
- On your PC, go to Start -> QPST -> and run the PDC program in Admin mode.
- In the PDC program, click the Device dropdown (yes, the UI is awful) and select the thing there.
- Look for "Oversea-Commercial_DS", right-click on it -> Deactivate -> Sub0 and Sub1
- Click on "Oversea-Commercial_DS" again and click the remove button.
- Restart the PDC program and select your device again.
- Pick "India-VoLTE-Vodafone", right-click -> SetSelectedConfig -> Sub0 and Sub1
- Click on "India-VoLTE-Vodafone" and click the activate button.
- Restart your phone! You can now disable the Serial/Full-Port things.
- Go to Settings -> Wifi & Internet -> SIM & Network -> SIM1/2 -> Enable the VoLTE things there too.