I clearly remember when Caller-ID first became available. I also remember thinking this was a great idea in that I could now see who was calling before I picked up the phone.

Since it began, Caller-ID has added many improvements, but it's not all one-sided. A caller can block Caller-ID using the *67 prefix. Calls made that way display the word "Private Call" or something similar on the recipient's Caller-ID display.

However, the recipient can activate something called "Anonymous Call Rejection." When that's activated, anyone trying to use the *67 prefix will hear a message saying something to the effect that the person they are trying to reach is not accepting blocked calls.

And so the great Caller-ID battle came to an end with all of these nice checks and balances in place. Until now.

"Spoofing"

The technical term for it is "Caller-ID spoofing." It was available only to law-enforcement agencies, private detectives and geeks who knew how to do it. Now, with the help of the Internet and some Web services, you can do it, too.

Basically, Caller-ID spoofing is a way to trick the Caller-ID display into showing a number different from the one you're calling from.

As with any tool, you will find both good as well as bad uses for it. My mission is not to get bogged down in an ethical debate about its use, only to alert you to its availability.

There are several of these Caller-ID spoofing Web sites out there, but let me tell you about the one I found that goes the extra mile. In addition to Caller-ID spoofing, it has some additional abilities that can enhance the spoofing experience.

You begin by calling their toll-free number and dialing your identification code. After asking you for the number to call, it asks you to key in the number you wish to be displayed on their Caller-ID box.

Whatever number you select, the state and city name that corresponds to the area code and prefix of the number will be displayed on the name portion of the Caller-ID display.

Choose your gender

The next option lets you choose to disguise your voice. You can select either male or female, with the male voice having a slightly better quality.

You're not going to fool anyone with these voices, as both of them sound electronically processed. Still, either of them will effectively disguise your voice from its actual tonality.

The other option you can choose before the call is placed is to record the conversation. If you choose this option, both sides of the conversation will be recorded.

After completion, you log on to the site. There waiting for you will be a downloadable wave file that contains the conversation you just had.

In fact, it keeps a complete log history of all the calls you made along with the date, time, duration and associated wave files if you requested the conversation be recorded.

As to the legality of all this, the Web site will not allow its service to be used placing 911 calls and will not dial toll-free numbers.

It says federal regulations prohibit the use of their technology by telemarketers or debt collectors to hide or falsify their phone number. There's nothing there that talks about its use by private citizens.

So in this world of growing identity theft and the loss of privacy, another tool that helps you to see who's knocking at your virtual door bites the dust.

I'm not saying to throw away your Caller-ID box, as it's still a useful product. Just know that from now on, the Caller-ID number you see may not be the number actually calling.

I can guarantee the bad guys already know all about this. Now, at least, you do, too.

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