[doesnotexist]

Wouldn't it be nice if you could give out a revokable token in place of a phone number to various businesses. If you ever received spam through a token just revoke it and move on. Puts the power back into the hands of the recipient rather than having to rely on some centralized service or your carrier.

[Anamon]

Unfortunately, many spam callers don't even use number lists, but just iterate through. phoneNumber++ ad infinitum. With parallelised robocallers that only involve a human when a connection is established, it's cheap and effective.