Do Universal Page support prefill of phone number?

Unfortunately, I can’t set hint of country phone code…if I set phone number into login_hint, I go to the page where country phone code of chose is code of my country, but how can i make this login hint for phone number?

I’m talking about New Universal Page

ok, post can be closed. If I submit login hint with the starting of phone number like “+48”, it prepopulates phone number accordingly.