I have an Optus branded S9+ still under warranty redeemed from tech fund and out of contract. I have since moved on to Vodafone. Problem is VOLTE has been disabled by Optus and I could not figure out how to enable it. There is no VOLTE option under Settings>Connections>Mobile Networks. How to get VOLTE?
This would be due to the unit having Optus Firmware.
In the past you needed the carriers firmware in order to get VoLTE (except iPhone).
Vodafone state this:
If you have an Android device and it’s Voice over LTE compatible, Voice over LTE should automatically be enabled.
If you have a device that wasn’t purchased through Vodafone, we can’t guarantee that it will be compatible with Voice over LTE on our network.
If there are any Optus rep here, please let me know if I can get the VOLTE restriction lifted? I tried contacting Samsung and they won't help.
VOLTE is already activated on my Voda sim. I know that because I get VOLTE when I insert the sim in an Oppo A73.
It has nothing to do with any Optus restriction at all - its a firmware limitation where Vodafone needs their firmware on your device in order to provide VoLTE.
I now have VOLTE and wifi calling, thanks to self-help and XDA forum.
I have successfuly flashed and removed 2 persistent carrier files that appeared under "Get recommended apps", My Optus and Operator Settings. Both these files remain persistent even after Odin flashing with Pie XSA. The only way is to get into the guts and by brute-force replace OPS with XSA.
I am also facing similar problem that you were facing. I have my phone from Vodafone and moved to Optus now.
When I insert Vodafone sim, VoLTE is enabled but when I insert Optus sim, it's not enabled.
I tried flashing the Optus firmware with Odin by downloading from Sam mobile. However, after flashing, at the boot I got 2 persistent carrier files that appeared under "Get recommended apps", My Vodafone and Operator Settings.
Could you please let me know how to replace this with OPS and enable VoLTE?