Don't answer! Unless you want to go to the plays, which are good. If you don't have the extra money or are not interested, don't pick up. They are real pests.
I've gotten repeated calls from this number as well - have attended some of the shows, and donated a few times, so obviously somehow got on their list. Would appreciate it if they stopped calling me! I will happily donate when/if I have cash flow.
I bought tickets to one of their shows a few years ago. They have haunted me by phone and email ever since. I am fairly well plugged into the arts community in NY so I have no particular need to be notified of what's playing and where, yet they hound me at least three times a year for a week or so worth of missed calls. I've instructed them to take me off their list. I will never attend any of their shows now as a result.
If you don't want to get calls from theaters, when you buy tkts to future shows and pay on your credit card, make a note that you don't want to be called. Round a bout theatre is a subscriber based company and the calls are actually to your advantage. As a subscriber, you'll be saving money on broadway shows. The calls are courtacy calls to patrons who purchased full priced tickets in the past. As a subscriber, you not only would be saving a lot of money, but you would also have great flexibility in your schedule and get free exchangeable tickets. If you don't want to be called in the future, pick up the phone and tell the rep to put you on their Do Not Call list. They will gladly do so.