The three great public instant message suppliers are to open up their networks - but only for businesses.

AOL, MSN and Yahoo! are backing an "unprecedented collaborative effort" to support Microsoft Office Live Communications Server 2005. Using the software, companies can reach customers etc. through all the major IM networks.

Interoperability was once the great clarion call for instant messaging, but the clamour has died down recently, even though IM is becoming ever more popular. This may be because AOL has long lost its effective public IM monopoly.

It does not appear to be particularly difficult -technically - to IM people from different networks. This, after all, is what Trillian users can do most of the time - Yahoo! occasionally blocks the service, but Trillian developer Cerulean is on the ball, usually producing patches within a day, readers report.

According to Microsoft, its enterprise customers' top request was to enable connectivity with major public IM networks. But companies are wary of public IM, calling instead for enterprise versions - i.e. with proper security features. But how many companies are paying for enterprise IM? Not enough to support Yahoo! which recently scrapped its enterprise IM product, or AOL, which decided to concentrate on reselling another company's product.

Live Communications Server 2005 launches in Q4, at which point pricing will be revealed. ®

Related stories

AOL unveils IM for business
Interoperability is long-term goal - IM vendors