Select the Data Extension column holding the phone number.
2. First name field
Used in the greeting: "Hi {Name}, your appointment is scheduled for..."
3. Appointment date field
Spoken value should already be formatted the way you want it read aloud (e.g. "July 5th at 3 PM").
4. What this activity does
Calls the contact, plays "Hi {Name}, your appointment is scheduled for {Date}. Press 1 to confirm, or press 2 to cancel."
The keypress is written back to this Data Extension's Confirm column as Y or N.