[posguy]

Yes, T-Mobile and a few other carriers support videocalling right in the Android dialer.

https://www.t-mobile.com/support/plans-features/t-mobile-vid...

[cyberax]

I've seen it work _once_, around 8 years ago on a T-Mobile branded Galaxy S phone.

I don't think it still works, and/or it requires some strange confluence of events to work.