For roll call, I will do a poll, ask a question, preferably not a "yes" or "no" question, such as, "how old should a girl be before she gets married," or, "what is your favorite pet animal?," or some other question related to the topic of the class, such as, "which of these three festivals in the textbook would you like to go to?" That way, every kid in class is speaking English at least once during class, and I am interacting and reacting with the kids as I call their names. I work at at a vocational institute with college-age kids.
Bonus, I also get a humbling demonstration of who has actually been listening to me, because some kids are caught by surprise every time and the answer is "huh"? When that happens, I continue with the roll call and return to the kid who wasn't prepared and ask them again at the end.
This year my classes only have about 16 to 20 kids per class.