Former MSI member as well. They've called at least twice this week, most recently at 11:20am cst on 7/15. I don't answer unknown numbers, especially from cities I don't know anybody in, and they haven't left a message.
Since their first call on May 14 whomever this is has called more than10 times with four calls so far today. I wrongly interpreted my caller ID as indicating that this was Chicago's Museum of Science & Industry where my membership lapsed over a year ago. However, the area code is wrong for Illinois. Even were this a legitimate New Jersey science institution, which I serioiusly doubt, it would not have my home phone number.
Based on the number of call attempts, it's far more likely a scammer pfishing for personal information (i.e. a credit card number). Even the worst not-profits and charitable organizations (the National Rifle Association's telemarketer and political fundraisers are my current most frequent) is not as bad over a 10 day period as these people. DO NOT ANSWER.
Your post is interesting because I, too, had an MSI membership until about 2 years ago. This number calls me 5-10x/day, for the past couple weeks. Never leaves a message and I won't answer. I wonder if there's a "Chicago" connection ot this or a MSI connection (i.e., someone there who gave out member info). ????