IBM, whose secure messaging system is used within many of the biggest companies, today said its customers would soon be able to chat with users of instant-messaging products from America Online, Yahoo and Google.

IBM said it plans by midyear to allow its Lotus Sametime corporate instant messaging system to work with the three consumer messaging systems, marking the latest move to break down barriers that have separated instant messaging audiences from one another.

Missing from the deal is Microsoft, the most direct rival of IBM in the corporate instant messaging market, where customers often demand greater security and want IT managers to have the ability to audit what users say.

If corporate messaging systems are able to work with consumer IM offerings, office workers will be able to communicate instantly with friends or family outside of work.

The ability to interconnect the separate instant messaging systems from IBM, AOL, Yahoo and Google is based on an industry standard technology known as Session Initiation Protocol, or SIP.

IBM made the announcement at Lotusphere, its annual conference on innovations in its corporate e-mail, messaging and collaboration software.

IBM also said it plans to incorporate "click-to-call" Web-based phone-calling features into Sametime through deals with Avaya Inc., Nortel Networks Ltd., Polycom Inc., Premiere Global Services Inc., Siemens AG and Tandberg ASA .