Pretend I am a phone company.

I will have several lists of companies. A list of banks, a list of phone companies, a list of insurance companies etc.

As part of the service, the customer's phone can block entire lists of companies and the customer can make exceptions to that list.
For example, he can choose block calls from every phone company, except mine (so we can contact him if needed)

The telephone apparatus should have a button that adds an incoming call's origin as blocked.

Blocked calls should be saved so the owner could screen through them if needed