I kept getting these calls every other day and if I don't pick up they don't leave a message. After reading this page I found that it was the California Academy of Science in San Francisco that kept calling me. I had a membership with them last year, but never really used it, so didn't choose to renew my membership. The number is asking for donations to the California Academy of Science. I emailed this address:
[email protected] and told them to take my number off the list. I received an email about 5 hours later stating that they were sorry and that my number would be taken off the list. So, email them and you can stop these annoying calls.