Gartner is warning enterprises to prepare carefully before they leap into the murky waters of public instant-messaging services, and should look at using new federated systems from the likes of Microsoft and IBM.

Such services show that IM networks designed for consumers are penetrating ever-deeper into the enterprise, Gartner says. While it is useless to resist the trend, companies need to be aware of the additional security risks, nuisance and expense that will inevitably be involved, according to the firm.

Gartner analysts David Mario Smith and Tom Eid published a research note on the subject last week, prompted by IBM's announcement in late January that it would add federated IM to its Lotus Sametime product, used by 15 million users. Sametime 7.5, due in the middle of this year, will use Session Initiation Protocol (SIP) to connect to AIM, ICQ, Yahoo Messenger, Google Talk and Apple's iChat.

"This announcement shows that IBM is very serious about IM interoperability, and is trying to strengthen its enterprise IM presence," Smith and Eid wrote.

Last year Microsoft made a similar move, giving its Live Communication Server access to public IM services for a fee of $10 per user. The Sametime feature will be free of charge. Gartner expects more such deals to be announced this year.

Such deals are likely to push forward a trend that has already become clearly established: that enterprises have largely shunned corporate-orientated IM systems in favour of networks originally designed for consumers. IDC found last year that there were 28 million IM users in the enterprise, largely on public networks, sending around one billion messages a day.

Gartner estimates IM is a key application in 70 percent of businesses, most of which use public services - the leaders being AIM and ICQ. Corporate IM systems have few users so far, and while Gartner expects them to gain ground, their users still tend to use public networks to communicate with the outside world.

However, consumer IM applications aren't designed for security or manageability, and public IM networks are becoming increasingly dangerous places to hang out. In one study, IMLogic found that security threats on IM and peer-to-peer systems increased by a factor of 3,295 in 2005.

Businesses probably can't avoid tangling with public networks, but can ease problems with adequate preparation, Gartner said. "There is no longer any excuse for not adopting corporate IM," Smith and Eid wrote. "But businesses should establish policies for connecting with external parties, to ensure public IM services are used for real business purposes."

Gartner also recommended that companies put "hygeine services" into place before allowing access to public IM networks. Such services, from the likes of IMlogic, FaceTime Communications and Akonix Systems, offer spam and virus protection, and will cost at least $10 per user to install, Gartner said.