When we got calls off a waitlist last year, it usually showed that school’s phone #, and a live person (i.e. school clerk) made the call. The waitlist offer would post the next business day at 8AM in gocps, and we’d have 48 business hours from then to accept or decline in gocps. Soon after the waitlist offer posted online, we’d also get a robocall (# is something like 773-553-5700) and email saying to check gocps because there was a change in our waitlist status at a school we had listed. If you know for sure that you don’t want an offer, I would suggest declining it without waiting the full 48 hours so that the school can move down its waitlist to someone else. It’s the nice thing to do.