The world's largest IT and communications vendors are divided in the way they intend to offer unified communications.
Unified communications is an evolution of voice/data convergence that aims to bring together voice, data, video and presence features into a single system to make an organisation's technology infrastructure simpler and its workers more productive.
All of the major vendors offer some form of unified communications, but they're starting to differ significantly in how they plan to deliver it.
Microsoft, which has just launched its Office Communications Server 2007 offering, believes that the intelligence behind unified communications should be contained in the endpoints, whether that is a desk phone, mobile device or a PC.
PBX vendors -- notably including Cisco -- disagree. They say the network is fundamental to the success of unified communications.
"If you rollout [unified communications] across a network, and you can't manage that network [then you have a problem]," said Warren Barkley, Microsoft's group programme manager for unified communications.
"If you put intelligence in the endpoints and servers, then you get around a lot of that," he said. "If endpoints have the ability to adapt [to changing network conditions], then you have flexibility."
A spokesperson for Cisco's unified communications unit disagreed. "The key is network functionality that can support real-time voice and video with quality of service that you can build out from," he said. "We try to simplify [unified communications] by adding features to the network," the spokesperson added, citing quality of service, network management tools and multiple codecs as three examples.
Cisco's unified communications offering revolves around its CallManager PBX software.
Rob Bamforth, an analyst with industry watchers Quocirca, argued that it is imperative that unified communications are developed using open standards. The largest vendors, including Cisco and Microsoft, have often developed proprietary software.
"Interoperability is still a challenge," said Bamforth, adding, however, that the vendors were getting more open in their approach, particularly because of the prevalence of IP.
"In terms of their particular implementations, they will want to keep their cards close to their chests," he said. "They need to innovate around the standards. With open standards, they don't need to be secretive."
ZDNet.co.uk's Richard Thurston reported from London.