A group of doctors notice that many patients have mobile phones and so send SMS reminders to these people informing them of an upcoming appointment. They ask for a reply to confirm the time or to alternatively reschedule.
However, they also notice that many patients do not have mobile phones, or have indicated that they prefer a voice phone call to remind them. They set up a preference system so that the reminder is sent in the manner in which the client wants to be communicated with. They reduce no show appointments from 15% to 5% creating a more efficient health practice, and more revenue for the doctors.
A doctor is running late, so the system sends an automated message informing the customers about the delay so that there is less frustration waiting for the scheduled appointment time. The key is in designing a system that works for your customers and business to achieve your goals.