Hey, @Kimwil, thanks so much for reaching out! Would you mind giving us information about your device?
* Model Number
* Baseband Version
You can find that information in Settings > About Phone.Thanks!
This option was available on my unlocked Note 8 running version 7 of the OS on Verizon's network.. When Oreo 8.0 was pushed to my Note last week the video calling option was deleted. When attempting to use IMS to turn on the option it fails. Under Oreo you need su yo turn on the option and the only way to obtain su is to root the phone. Why Samsug would disable this option unknown. So your only choice is to root the phone or hope Samsung issues a patch to allow video calling to be entitled on unlocked phones.
I really appreciate you taking the time to reach out to us about this. Were you able to get that information to us?
If you need help with anything else, please let us know and our community will be happy to help!