In Portugal all carriers have had free sms between all carriera for a few years now on almost all plans. I believe people still reasonably use it. Mobile data cannot be assumed to be always on as it is too expensive most of the time and never forget that having mobile data on drains battery too fast. If anyone wants to be sure to that someone replies to something in urgent matter better use standard sms/phone calls. I havr no idea in what kind of bubbles people are mostly nowadays. Anyway, almost everyone has whatsup or telgram too and most people also use those as a main way to communicate and mostly to be in chat groups. I'm the weird one using only sms and signal and very little of facebook messenger.