Families live underground, contact is forbidden, but the protagonist kids want to meet and eventually also escape to the surface, which seems to be a desert.
The air is breathable, contrary to what they are told.
The boy and girl communicate through a big screen, which takes up almost the whole wall. (As do the aduls too with other adults of other groups/families.)
It's probably a dystopian sci-fi, so tunnels instead of caves and no magic.
I very faintly remember some kind of slide/capsule system for transportation, but this might just be my brain trying to come up with details that are simply incorrect.
I saw this in Hungarian sometime in the early 90s (not in a cinema, so it's probably made in the 80s). So this could be a B-movie, a direct to VHS TV show, or who knows what.
It's not City of Ember.