[RandomBacon]

I think it's a combination of

- people giving their phone number out to companies that share this data, and

- people answering spam calls. Even if you hang up immediately, they probably have an internal metric that says call that number back more frequently.

I don't do either of those, and last week I had more spam/unknown calls than usual: 4

For online forms that require a phone number, I just insert that company's own number.