See The 9 Best Call Blockers on Ezvid Wiki ►►
Fact #1. A large preprogrammed repertoire of robocall and scam numbers is crucial. This will make the unit more effective from the outset. It will also require less of your time to add additional numbers. Some units may come with as little as 200 numbers, while others may have well over 1,000. Another feature is the ability to add new numbers after hanging up a call by simply pressing a button. Some models have a button on the top that will block the last number that called.
Fact #2. In general, more automation is better. Some can automatically block any number with no caller ID. Many sales and marketing callers hide their number, as do many collection companies. These are prime candidates for blocking. Try and avoid models that depend on you to spend a lot of time managing whitelists and blacklists. This can be very time consuming and some may find it overly complicated.
Fact #3. The best way to think of these is as a combination caller ID and answering machine. First, the caller ID component identifies the telephone number that the call has originated from. If it matches one of the numbers on the block list, it will automatically answer the phone for you. Then it will play an automated message telling the caller that their number has been blocked.
Fact #4. They're able to identify the number because every phone number is like a fingerprint. When a person makes a call, their number is transmitted along the phone lines as a series beeps at varying frequencies. This code can be read by the called phone and then displayed to the person being called. Cell phones do this automatically, but most traditional landlines need a separate device.
Fact #5. This transmission happens even with hidden numbers. Some companies use automatic call blockers that are integrated into their phone systems. Or they might subscribe to a service that does it for them. Either way, that only works at the level of caller ID. These models will bypass that issue.