Wifi calling has to be included in your package or it can't work. In the pulldown menu my Note8 has the option to turn it on. And it only works on a wifi connection.
Samsung khmer keyboard is better yet as Samsung English or Chinese keyboard , Samsung khmer keyboard doesn't has more option as English or Chinese keyboard that has
dictionary help and handwritting keyboard.
If we compare with Gboard of Google is Samsung it has a low level yet.