From below dialogue ,What's the difference between "start + to + verb" and " start + present participle" here? and what's the red highlights ? thanks for your always help!

Man :All of a sudden, the phone starts to ring. Now I don't know what to do, everybody starts looking at me.

Woman:And they weren't looking at you before?!

Man :Finally, I figure I'd better answer it, and it turns out it's my mother, which is very-very weird, because- she never calls me!