If you screen your calls -- and never answer an unknown number -- then this product is for you. Privus Mobile gives certain smartphones X-ray vision when it comes to caller ID and tells you exactly who's calling, even if the number isn't stored in your phone's contact list.

I am very selective about answering my phone. Because I use it for both personal and business calls, I like to know who is calling me before picking up. The problem is, if someone who's not in my contact database calls, all I see is a number. I don't know who or what company is behind that number. What's worse, I receive a lot of calls from "unknown" numbers, which don't even display a number with an area code that I can guess at. These are a complete crap-shoot at answering, it could be anyone.

That's about to change, at least for some users of BlackBerry and Windows Mobile smartphones.

Enter Privus Mobile. Privus is a subsidiary of Accudata Technologies, which has its tendrils spread into most of the major telephone directory services and databases. You have to download the Privus application to your smartphone, and once you do, any calls will display the name that is associated with that number. That could be an individual, or a corporation.

If someone has a blocked number, that number will still show up as blocked, and Privus won't display the caller ID information. Pretty much any other phone number that it can look up, it will provide caller ID information for. It doesn't matter if that person calls from a mobile number or a landline. They also don't have to subscribe to the service. As long as the person being called is signed up, they will see the caller ID info.

There's a catch, though. If you think that service is worth a few dollars a month, prepare to get bummed out. You can buy three months of service for $25, or 12 months of service for $90. That's $7.50 per month, which means it is a premium service.

The service does offer one more perk. "People are receiving more and more calls on their wireless phones, and they want to know everyone who's calling them, but this Caller ID service that was commonplace on home phones just hasn't been available on wireless phones until Privus," said I D YOU President Greg Smith. "One of the additional benefits of the service is that Privus Mobile will save the caller's name and number into your contact list with the push of a button; or automatically if you wish. No more tedious entering names for every new person who calls you -- when they call, you'll get all of their contact information on your display."

If screening calls is that important to you, then perhaps Privus Mobile is worth the price. For the rest of us, that might be a bit out of reach.