I have also been receiving calls from this number for several days now in the morning and at night. For anyone that ends up here, you can call the number back and there is an automated system that will remove you from the call list. I just recently subscribed to San Francisco Chronicle, which is likely why they are calling me even though I already paid.
This person called me twice today. The first time, I let the phone go to voicemail and no message was left. The second time, I picked up but nobody responded when I said hello.