Oct. 11--You would think it was crazy if your cell phone could call only people with phones on the same network.

But we put up with that absurd situation when it comes to instant messaging -- and have for years. Worse, there's little sign of change anytime soon.

On a typical day, I have three -- and sometimes four -- instant messaging clients running at the same time.

I run Yahoo Messenger because it was the chat service we used when I worked at CNet News.com and many of my colleagues and some of my sources from those days use it exclusively. I run AOL Instant Messenger (AIM) because it was the chat program we used when I worked at TheStreet.com and it still provides me with the best access to many of my sources on Wall Street. And I run Google Talk because it's what our Web staff here at the Mercury News uses, and it's the best way to communicate with them when I need to tweak a story on our Web site.

On top of that, the editors here are pushing us to run a new IM program -- Spark. So far I haven't found it very helpful because only a few people use it and my computer becomes unstable when it's running.

Running that many different instant messaging clients is a constant frustration. They suck up memory and processing power, slowing down -- and sometimes crashing -- my PC. When I want to send someone an instant message, I first have to remember what chat

program they're on. But if I want to remain accessible to my contacts, I have little choice but to have all those programs running at once.

You'd think this problem would have been fixed by now. Internet chat programs have been around since the late 1980s and hit the mainstream in the mid-1990s with the popularity of applications such as ICQ and AIM.

Way back in 2001, the Federal Communications Commission identified the lack of interoperability among these services as a major issue. As part of the AOL-Time Warner merger, the FCC barred AOL from adding advanced features such as video chat to AIM unless AOL allowed chat clients from competitors such as Microsoft and Yahoo to work with AIM.

In the wake of that ruling, there have been some stabs at interoperability. Yahoo Messenger users can send messages to Windows Messenger users and vice versa. Users of Apple's iChat can send instant messages to AIM users and Google Talk users. Many chat programs consumers use, such as AIM, are interoperable with some chat programs used by businesses.

But the FCC let AOL off the hook and backed off of its push on interoperability in 2003. Since then, there's been little movement toward a unified instant messaging system.