But the process of integrating voice and data began well before that, with the technology that underpins most unified communications - voice over IP (VoIP). Unified messaging gave an additional boost to the emerging technology.
But it was not until suppliers began trying to remove the distinction between fixed and mobile communications and introduce services such as presence software (dashboards tells the user how best to contact someone), instant messaging and desktop video conferencing that unified communications got going.
"Microsoft's entry helped unified communications to really take off, as hard as it might be for a competitor to admit that," acknowledges Jirina Yates, EMEA solutions marketing director at Avaya. "However, Microsoft is on release one, we are on release 50 and we are not approaching unified communications from the desktop but from a business need."
This year Avaya launched Intelligent Presence, software that collects presence information from telephony and desktop applications from third parties including Microsoft and IBM. The company also introduced Unified Communications Solutions, lower priced packages for different types of businesses including stores and banks.
Meanwhile, Microsoft has built its portfolio around three core software products: Exchange, its Office Communications Server and Live Meeting. Microsoft Exchange handles e-mail, fax and voice mail. One fifth of Exchange deployments now have an element of unified communications in them, says Mark Deakin, unified communications product manager for the company.
Office Communications Server delivers instant messaging, presence services, as well as audio, video and web conferencing. In many ways it is Microsoft's version of the private branch exchange. Live Meeting is a web presentation tool that allows users to exchange information during meetings.
NHS trust United Bristol Healthcare is a showcase for Microsoft's unified communications, says Deakin. Clinical staff - often resistant to new technology - can locate and consult specialists during clinical emergencies using Exchange 2007 and Office Communications Server. "As long as they see enough advantage, people will adopt the new technology," comments Deakin.
Despite the fuss, unified communications remains at the early adopter stage. Last year just 5 per cent of UK businesses had adopted the technology and only 18 per cent had prepared roll-out plans, says analyst firm PMP.
Cost, complexity and problems with incompatible systems are among the stumbling blocks for IT managers. The industry is responding with partnerships, joint research and developing open standards.
Private branch exchange (PBX) company Nortel's four-year research and development alliance with Microsoft - signed two years ago - underlines the big effort needed to weld traditional telephony with data communications. The pact involves integrating Nortel's IP telephony services with Office Communications Server and Exchange.
"Since January, we have been the first and only vendor - on our Communication Server 1000 - to reach Microsoft's IP PBX qualification for Office Communications Server," says Paul Rowe, Nortel's unified communications product marketing leader, EMEA.
Nortel has set up a collaboration centre with Microsoft in Maidenhead, where 500 Microsoft sales staff who serve unified communications customers across the UK.
Not all the big players are keen to collaborate. Cisco, for example, keeps its portfolio proprietry with a hardware-oriented approach. The company's flagship product is Unified Communications Manager, designed to deliver voice, video, mobility and presence services to devices that include IP phones, voice over IP gateways, mobile devices, and multimedia applications.
Another key element in Cisco's strategy is WebEx, a subscription service for web-based conferences and data sharing, which the company acquired last year.
Despite its 'not invented here' attitude, Cisco - in common with all the major players - supports the Session Initiation Protocol (SIP), a unified communications standard for making calls.
However, the company's UK communications sales manager, Mark Forster, stresses the importance of business processes. "In future, unified communications is going to be about collaboration and it will exist in applications such as SAP and Oracle. When someone working on accounts in SAP hits a snag they will be able to identify a colleague who can help them, find out if they are available and call them."
Cisco is not alone in wanting to embed presence functions in business processes. It is likely to be the next big thing in unified communications, as suppliers strive to deliver on earlier promises to boost productivity and improve customer service.
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