In what situation should parents bring their child to a speech therapist?

Options aren't very useful. There are milestones for speech that need to be observed. My kid wasn't talking or babbling much by 1.5 yrs old, not even mama or dada with intentionality. Got a referral to KKH Department of Child Development to get his professionally assessed and into speech therapy classes. I find that early intervention is so important and helped us to understand and learn how to help him.