When I look over the statistics and see the Google search terms for my blog, one of the larger keyword phrases I see is "how to use MagicJack with call blocking or caller ID." And I've good news and bad news. Officially, MagicJack does have caller ID and doesn't have call blocking. But there are a few nifty free tricks you can easily do to have those functions.
Since caller ID is the easiest let's do that first. MagicJack essentially keeps a log of all incoming (and outgoing) calls. And basically you just need to label the numbers. Once the numbers are labeled whenever you get a call from the number again you'll be able to identify the caller. So there you go "caller ID." It's easy, but a little bit of a speed bump. I think the real thing people want is the ability to identify "unknown callers." Guess what though? If the person calling you has chosen to hide their number you wouldn't be able to see it anyway. So back to square one no matter what phone service you use.
But I understand where all this leads; getting calls from unknown callers makes you want something to block them. And again, "regular" phone companies aren't really furnishing this service as much as they used to. I remember in the 90's being able to get call blocking and then the phone companies seemed to have stopped offering it and started giving out a "if the caller is harassing you fill out a police report, send that to us and we'll block the number" solution. I don't know why but the phone companies just wouldn't do it, or if they did not without a substantial fee. Internet based phone companies like MagicJack and Vonage aren't offering the service either. I was with Vonage for five solid years and no matter how much we complained they just wouldn't do it.
To the rescue comes a couple of internet solutions.
Until Google Voice is available I recommend that you get a free piece of software called "PhoneTray." It will work with your computer's modem to act as a first line defense with incoming calls. Among the many features it can do for free is it can also block calls. So in just a few minutes you can have a system that will give you a lot of peace.