Let's say you needed to keep a bunch of different phones on your desk: one to talk to your parents, one for your pals, one for your business contacts and one for your significant other.

On the positive side, after a bad breakup, you could throw the whole freakin' phone away. Oh yeah, that's closure.

But the fact that you live in a world in which every phone works with every other phone is a beautiful thing. This is why the current contretemps surrounding instant-messenger systems on the Internet is all the more frustrating. There are nearly half a dozen IM brands, including two from dominant player America Online, but the systems generally can't talk to each other.

The Internet's uber-geeks keep building doodads that will let you link your preferred instant-messaging system to anybody else's. But the corporate giants behind the systems are fighting pitched battles to keep their IM lines closed. The one everybody is talking about--Trillian--works swell, but the suits will break it the first chance they get.

The telephone system avoided this problem because it was developed by a monopoly that had a vested interest in making all the equipment interoperable.

In fact, you could conclude that what the instant-messaging world really needs is a good, old-fashioned ruthless monopolist to impose a little order. Or some federal regulators with a little backbone.

The Net is famous for breaking the stranglehold of proprietary technologies, such as America Online's long battle in the early '90s to avoid letting its subscribers exchange e-mail with the rest of the world. But not even the power of free and open standards has forced shortsighted, greedy, malevolent companies such as AOL to let their proprietary systems work with IM systems run by other companies. As a result, many users wind up stuck with multiple versions of instant-messaging systems loaded on their computers.

Almost 48 million consumers use one of America Online's two systems, AIM and ICQ, on their home computers. Microsoft's MSN messenger has almost 19 million, and Yahoo's service has nearly 12 million.

Companies such as Microsoft have repeatedly tried to link their instant-messaging systems to AOL's. But AOL considers that to be hacking and has repeatedly rejiggered its instant-messaging software to break those links.

This behavior was a key concern during AOL's purchase of Time Warner, which received regulatory approval in part because AOL agreed to work on ways to develop a safe and reliable IM standard--but not until it starts offering advanced services, such as teleconferencing.

This is why a product like Trillian probably will stop working about three seconds after this column hits the street.

Trillian works with all the major instant-messaging systems. Launched last year, a recent, more fully featured upgrade has led to a lot more users, who now total about 300,000. You can download it for free at [link]

Why does anybody care about this? "Everyone I know uses some kind of instant-messaging or chat system, but I didn't want to have five pieces of software on my PC, all running at the same time, simply so I could chat," said Bryan Anderson, a 31-year-old air-conditioning service manager who lives in Britain and recently downloaded the program. "Trillian means I can chat to anyone through one piece of software."

AOL is not pleased. "We think interoperation has value for consumers if it's done in the right way," company spokeswoman Kathy McKiernan said. "But we are opposed to efforts to hack into our systems and endanger the privacy and security of our members."

A noble sentiment. Unfortunately, instant messaging is inherently insecure. Experts say it's not safe to put sensitive information on such systems.

The fact is that AOL doesn't make any money from instant messaging at the moment, but it hopes to one day "monetize" the system. And to maximize its profit, it needs to keep people from using other products. Hence the move to block interoperation.

Fortunately, there are guys such as Scott Werndorfer, co-founder of Cerulean Studios, which makes and distributes Trillian. He says if AOL breaks the current version of Trillian by rejiggering its instant-messaging system, his crew will in turn change Trillian to try to keep it functional.

"We're working on the next release right now," he said.