IM interoperability--at least for business.

Research firm IDC estimates that as many as 255 million people will use instant messaging (IM) at work in 2005, up from 65 million in 2002.

That estimate may have to be revised because using IM at work is about to get much easier, even if it will no longer be free. One of the main stumbling blocks to the widespread use of IM technology has always been interoperability. In other words, MSN Messenger users have not been able to send or receive instant messages from Yahoo! or America Online (AOL) IM users.

But soon, IM subscribers that use different IM networks at work will be able to communicate with each other. Microsoft recently announced that it will open its IM software used by businesses to AOL and Yahoo's systems.

Microsoft's separate messaging software allows businesses to install IM within their corporate networks, where conversations can be monitored and saved, much like enterprise e-mail. The ability to connect to AOL and Yahoo's IM networks will be an add-on feature to the next version of Microsoft software that enables messaging, called Live Communications Server, due out by the end of the year. It will allow business users to employ a single software program to send and receive instant messages from AOL, MSN, Yahoo, and other providers if they first set up an account with each service. Companies will have to license the Microsoft network software, which will act as a hub connecting the separate IM networks.

As part of the partnership, officials said Microsoft will receive a license fee from companies for its network software and support, and it will then pay unspecified fees to AOL and Yahoo. The effort will not be operational before early 2005, analysts say. The new service will include features that free IM services do not, such as the ability to electronically record and save instant messages, and will guarantee secure communications. According to The Washington Post, the ability to store and retrieve instant messages is critical for businesses placing orders with suppliers, brokerage firms confirming stock prices to investors, and in numerous other commercial transactions and communications.

IM technology has also been a hit among consumers, but they won't be able to take advantage of Microsoft's announcement because the company is not extending the same interoperability capability to general users. Even without interoperability, AOL says more than 2 billion messages are sent and received on its network daily, surpassing the 400 million e-mails sent daily by AOL users.