Ring Doorbell for Gift Certificates

On Saturday night I went to dinner with Rose and Noelle. I wanted to stay home, make Valentine's Day cards and not spend money, but Rose had been dealing with her uncle's funeral that day, and Noelle had attended two funerals, so I thought I'd oblige them and go to dinner. Plus, who am I to turn down going out? We went to the Bombay House for Indian food. I'd only been there once when they were at the old location, so I was excited to try it again. The restaurant moved a few years back, and they're now in an old Outback Steakhouse building. They've redecorated, but the seating is still the same, and it still has the hardwood floors, so it looks kind of silly. Anyway, we had a great dinner and when we left I noticed this outside the front door of the restaurant. It's a little sign with a buzzer below it that says, "Ring doorbell for gift certificates," and I thought it was kind of comical. Does one merely ring the buzzer and they're handed a gift certificate through some trap door mechanism? Does an employee come outside to help you? Not exactly sure how it works, but it's funny, nonetheless!