Some analysts, and quite a few vendors, argue that the cost savings of shifting from traditional phone systems to voice over IP (VoIP) can be as much as 90 per cent.

But nothing in life is quite as simple and, despite the efforts of vendors such as Cisco to promote the benefits, the take-up of VoIP has been slow.

The issues surrounding IP in the enterprise are the basis for a conference and exhibition to be held later this month in London.

Last week, vnunet.com's sister title Computing brought together some of the interested parties to hammer out the issues at a roundtable event.

One of the big issues is take-up. Are organisations pressing to switch to VoIP? Can users find real-world examples of VoIP, or is it all supplier marketing?

Initially it was a case of vendor-driven hype, according to James Knowles, IP marketing manager for Siemens Communications.

"IP was a technology pushed by the likes of Cisco but, because of some of the early successes, customers could see the benefits, particularly in IP trunking and savings on the Wan," he said.

"The traditional carriers and telecoms equipment manufacturers could then see the benefits, and now users are calling us in and saying they can see the benefits."

Michael Robinson, vice president at IP and communications specialist Vegastream, also points the finger at Cisco, but believes that the company was driven to it.

"I think it was the case that the likes of Cisco couldn't compete with traditional products and had to market IP. The traditional PBX vendors responded and that kicked off a hype cycle," he said.

"They had to respond with their own story [on IP] and I think in many cases that is exactly what it was: a story.

"They all felt obliged to match each other's hype and there was a big overshoot of the users' knowledge and expectations."

Is the market beginning to move towards convergence of voice and data? "I think the market is starting to dip its toe in the water on convergence," commented James Burns, sales manager at channel supplier IP Integration.

"But there is recognition of the issues and problems in delivering voice over an IP backbone. The take-up hasn't been as quick as many people would have liked."

Knowles highlighted the issue of existing communications infrastructures. "The infrastructure needs to be done first," he said.

"Either they do it all in one big hit, or they will roll it through. It's a fairly clean migration: going from the Wan to the Lan and then the applications."

But how easy or difficult it is to fix the infrastructure depends on who you are. "It's different for different people," said Alcatel sales director Neil Garnett.

"Legacy customers are much more cautious about the deployment of mission-critical applications, especially voice. They have been hit by the reality wave. The hype has ebbed away, and reality has returned to a lot of customers."

The difference is between 'green field' sites and legacy sites. "The green field sites will push it a lot more than the legacy," said Garnett.

The reasons for adopting convergence also depend on who you are. Organisations are moving to adopt convergence for cost reasons, for extra features and services, or both.

"If it's a green field site, customers are looking for better service," said Garnett. "People in these sites have moved on and are much more sophisticated in their demands and expectations. They want much more from technology suppliers. They are pushing us."

So where are the benefits for legacy sites? "It's in cost management savings, and deliverables in terms of the sort of solutions you can put over an IP network compared with legacy systems," said Burns.

"I haven't been in a green field site yet where a customer wants to continue with traditional telephony. The legacy is more difficult. They are far more cautious. It has to be a phased approach."

Knowles agreed. "Certainly green field sites are the ones that push the envelope," he explained. "They are looking to get more from their technology and to leverage their investments. You need to have a much richer blend of convergent applications to get the economies of scale."

But even in green field sites, IT and network managers can meet resistance from users.

"IP gets a bad name when you go in with a big bang approach. As soon as something goes wrong, everyone points the finger at the IP equipment," warned Burns.

"That's where you get this market perception. They think: 'If we go IP, I am going to pick up the phone and not get a dialling tone,' and that is problematic."

Robinson believes a way around this is to focus on the cost benefits which can make a compelling case, especially when twinned with one of the strongest features of the IP approach.

"It tends to be either the classic savings on call charges, or the second classic application of dealing with remote offices and remote workers," he said.

"Bringing them into the infrastructure of the company can be difficult, expensive or impossible with traditional infrastructures."

Making secure that remote working possible is one of the key applications for convergence. But that makes dealing with the infrastructure more of an issue for many IT departments.

The ability to enable remote and home working is a really compelling application of convergence, Garnett believes.

But is it a popular application? "Do we have many people doing IP-enabled home working? I wouldn't exactly say we could fill Wembley Stadium with them. But yes, we are seeing people doing it," said Knowles.

Overall, while most of our panel agreed that the case for convergence is becoming more compelling every day, there is still much more persuasion needed.

European legislation on flexible working will help, but what is needed is more examples of proven, reliable applications. Even then, many may still be unwilling to fully entrust their mission-critical voice networks to data communications.

Like many ideas in IT, whatever the proven benefits, user caution may continue to win out in the short term.

GET MORE EXPERT OPINION

Computing is a media sponsor of the forthcoming Enterprise IP Technology (eIPt) exhibition and conference for senior IT professionals.

The event takes place at London's Olympia on 19-20 November, and will feature exhibitions and an educational conference to help IT and business decision makers choose the most appropriate enterprise IP products.

It will also offer an attractive programme of master classes, case studies, supplier keynotes and panel debates.

Among the speakers will be Sandy Fitzpatrick, senior analyst and director of Canalys, who will discuss market trends and forecasts for enterprise telephony. For full details go to www.eipt.co.uk