Business users of MSN, AOL or Yahoo instant messaging (IM) will be able to communicate with each other by the end of this year.
Millions of people use IM every day in their business dealings but usually rely on free consumer products from the three vendors, which lack the business-level security required by corporates.
"In much the same way that email has significantly changed today's business landscape, IM is becoming just as ubiquitous in organisations," said Anoop Gupta, corporate vice president at Microsoft, in a statement.
"Businesses are enquiring about ways to extend enterprise IM systems beyond network borders to empower their employees to connect more securely with customers, partners, family and friends."
Users of MSN, Yahoo and AOL IM can currently only communicate with people using the same package.
But the companies believe that a more robust and integrated business product could help drive the adoption of corporate IM services.
New interoperability will be made available using Microsoft's Live Communications Server 2005, due out at the end of the year.
"At that time, customers will be able to try the connectivity offering to the AOL, MSN and Yahoo IM networks," said Microsoft.
Pricing and licensing options will be finalised later this year.
New light-guiding nanoscale device can control and monitor a nanoparticle trapped in a laser beam with high sensitivity
Optical traps are scientific instruments in which a focused laser beam is used to exert an attractive or repulsive force on a microscopic object to hold it in place
Scientists estimate that the exoplanet has already lost up to 35 per cent of its mass over its lifetime
The observations were made using the Atacama Array in the Chilean desert
J1043+2408 was observed for more than 10 years, and its radio light curve exhibited a periodic signal repeating in about 563 days