The solution available on my land line is very simple, and works very well. Any call from an unfamiliar number get an automated prompt to enter a specific digi

The solution available on my land line is very simple, and works very well. Any call from an unfamiliar number get an automated prompt to enter a specific digit. The digit changes, and of course relies on the caller being able to follow this simple instruction. All of this happens before my phone rings. Once a call does get through (or even if it hasn't), you can review it on the telco web site, and either whitelist or block each calling number. Those that are whitelisted now get through directly, without the prompt, and then continue on as normal. No cost to the consumer either for this feature, but it isn't on by default.