How to enable 3G video calls on Android smartphone?

re.: How to enable video calls on Android smartphone ? In pre Android times it was easy to make video call on a standard phone, featuring small screen. Today video call functionality is not supported by most of makes, models of Android smartphones, for unknown reason. Ok, you need to establish 3G/ LTE data conectivity for video streaming as extra add-on- communication channel. Ok, I have 3G data transfer enabled and still no support for making video calls. I am not interested in third party video calling apps. I am aware, few smartphones by Samsung support video calling functionality. Is it due to licencing or for another reason. If video calling was supported by default 10 years ago and promoted at Barcelona Mobile Congress, so why today video calling in Android smartphones is not supported or disabled by 99% default. I read a lot on this subject on the Internet but all I need is to have video calling enabled in my smartphones and I can pay extra fee. Let me know your opinion and solution ( not interested in third party apps supporting 3G video calling) thank you BTW I was told (need to test it first) that Samsung 3G video calling enabled smartphone can video call my smartphone to enable 3G video calling on-the-fly, showing camera icon to click to pick up a call. If this is the case, so in theory, any Android smartphone can support 3G video calling ( 3G connection established and paid by third party) BTW2 I read related questions and answers one asked 8 years ago https://android.stackexchange.com/questions/10092/questions-regarding-receiving-3g-calls-on-my-ideos another asked 3 years ago https://android.stackexchange.com/questions/172824/how-to-video-call and still clear why no 3G video calling support on newer Android smartphones, since what is claimed: \ " what you are looking for is the operator backed 3G-324M solution that is available on most 3G phones (not including iPhone or Android). "