I am adding my experience here for others references.
I just moved to new country. I couldn't verify my new number from the new country. The error mentioned I should try another number. Customer service also said the same thing. And I don't have another number.
So, apparently, after I tried to explore by MYSELF what the problem can be, I found out I have to change my profile first (where I live in) before phone verification. Man... Airbnb should know better about this "features"