Robocallers are a modern plague. It wouldn't have moved Pharaoh to let my people go, it's true, but he sure would have sent Egypt's Secret Police out to teach the scammers a lesson — if he could have found them.
Everyone, it seems, is now concerned, and everyone, it seems, is offering free advice on how to deal with them. Why shouldn't I?
First, put an announcement message on your voicemail to let people know that their call may have been deliberately ignored:
Hello, you've reached the voicemail of [your name]. Either I'm unable to immediately answer your call, or I didn't recognize your number. Please leave your name, a short message, and a call-back number and I will return the call when I am able. Thank you and have a nice day. If this is a sales solicitation call, you will never get a return call. Have a nice day someplace else.
Second, adopt this policy: if a call comes through with a name or number you do not recognize, let it roll to voice-mail. Most cell phones will silence the ringer if you change the volume, so volume-up or volume-down and the ringer turns off. The call goes to voicemail after ringing (silently) for x times.
Third, do not block the caller. Many robocallers 'spoof' the incoming number; the number you're blocking isn't the number the call is really coming from. That means you will be blocking the wrong number. Worse, the number you block is probably a real, active, in-use phone for somebody, and you could be blocking a number that, sometime in the future, you actually want to be able to call you. And, because you're blocking the wrong number, it's a waste of your time and effort.
Some robocalls are really made by (software) robots. These programs only know that the call has been answered, not that it has been answered by voicemail. As a result, they begin their pre-recorded spiel as soon as the phone stops ringing. Since you let it roll to voicemail, the first 10-15 seconds of that spiel doesn't get onto your voicemail. When you finally listen to the message it says "...ether. If you haven't taken care of this...". The missing front end tells you immediately that it wasn't a real person, and you can safely purge the message.
Technology may provide some relief. T-Mobile, for instance, has an internal list of probable spammers and marks many incoming calls as "Scam Likely". Definitely let those roll to voicemail. Most of them do not leave messages, but some... The very best one I've ever encountered was an intelligent robocaller. It could hear and recognize voice responses and respond appropriately. It went something like this:
Me: "Hello... hello..."
Robocaller: (nervous giggle) "Oh, sorry, I was having a little trouble with my headset. Can you hear me?"
Me: "Yes, I can hear you."
RC: "This is Julie from ... and I'm calling to see if you..."
At that point I hung up, but did you notice how the conversation went? It waited for a second 'hello' before starting. Then, it gave a reason for not answering immediately, so you believe this is a real person. You respond with a 'yes', and the RC now knows it has a real person to 'talk' to, so it starts the spiel. If you let it go on, it will ask questions, collect the answers, and maybe later route you over to the real caller having established that you do have storm windows and still have a mortgage and have a decent credit rating. Insidious...
Legislation is unlikely to put a stop to this. When has legislation ever solved a problem without creating two more to replace it? When the law goes into effect, the spammers and scammers will alter their procedures or move offshore or... and the annoying calls will continue unabated.
Let them roll to voicemail.