Have you ever bought anything online? If you are unlisted or not, when you share your contact information for an online purchase, that data can be sold to database companies.
I just got a call from this same number. Computer generated voice asked if my husband was available. I said "no". It then asked to speak to the man or lady of the house. I asked who was calling. The reply coming from an automated voice said it was ...something to do with breast cancer.
I've gotten 4 calls from this number, three of them today. Sometimes the caller id shows "Seattle WA, sometimes just the number repeated. Will put the number on my list to be blocked.
People, it does no good at all to post "they called me but I didn't answer". And you can whine all you want about reporting them to the "Do Not Call" list, but that group is hopelessly understaffed to do any good.
This number is requesting donations to the Breast Cancer Financial Assistance Fund. If you call them back you can push one to (supposedly) be removed from their call list.