LONDON—Enterprise might already be using voice over wireless LAN, but the technology is still far from perfect, admitted networking and telecom executives at this week's VON Europe conference here.

Even the most bullish said that a host of problems, from security to ease-of-use, need to be ironed out before wireless VOIP (voice over IP) can live up to its potential and shake up the wireless voice industry.

"I believe the impact of this technology will be massive, disruptive and chaotic, but also opportunistic," said Graham Rivers, the former director of business development and strategy at T-Mobile.

"It could underpin true fixed-mobile convergence. But the challenge to deliver simplicity is colossal."

VOIP is making steady progress on fixed IP networks, where many businesses simply see it as a more flexible, cost-effective replacement for aging PBXes. Telecom companies are replacing their traditional infrastructure with IP.

Resource Library:

But wireless is another matter—to begin with, most standard wireless LAN equipment simply isn't good enough to carry much voice traffic, according to industry observers.

WLAN vendors are preparing products that address increasing user interest in VOIP. Click here to read more.

This was brought into sharp focus at the conference itself, where the WLAN was down as often as it was up—due at least in part to the larger-than-average number of VOIP users on the premises.

Brian Day, Nortel's vice president of wireline networks was brave enough to attempt an on-stage demonstration of the company's in-house VOIP system, which allows users to make calls from their laptops over any IP network, as though they were in the office; the call never connected. "The network has failed me," Day said.

BT, the United Kingdom's incumbent telecom operator, made no bones about the current inadequacies of wireless VOIP. Among the most pressing issues are the scarcity of WLAN bandwidth, the rarity of roaming agreements, expectations of low or free pricing, lack of quality of service, and difficulty of use compared with mobile phones, Cook said.

Wi-Fi coverage is particularly spotty in Europe because power restrictions make hot spots smaller than in the United States, he said.

Nevertheless, BT sees IP as the future—the telco announced on Wednesday that it will convert its entire network to IP by 2009, saving itself 1 billion pounds ($1.84 billion) per year in the process.

A key part of BT's plans will be the ability for a single handset to act as a cell phone outside the home or office, and switch to a WLAN or Bluetooth connection when one is available.

"Right now mobile and fixed are two islands that don't communicate," said Andy Cook, chief technology officer of BT's network mobility group. "We are building one converged network, where you'll be able to have one device, one number, one message box, one address book, one point of contact."

Increased hardware integration, including building low-power WLAN circuitry into mobile phones, will go a long way toward dealing with wireless VOIP's current problems, according to Tom Flanagan, Texas Instruments' worldwide director of broadband strategy.

"All the necessary tools to integrate are already in place for wireless IP phones and dual-mode phones," he said.

Wi-Fi-enabled handsets might have trouble dealing with the login, security and traffic issues of public hot spots, but those problems are less of an issue on enterprise and home WLANs set up to deal with voice, Flanagan pointed out.

"We see Wi-Fi complementing 3G, not competing at all," he said. "You'll use 3G when you're outdoors, and when you're indoors or in the office you'll use Wi-Fi—it will be integrated with your PBX."

As unimpressive as the technology might be at the moment, to many in the industry it looks a bit like early cell phones. Rivers recalled that in the early 1990s, when the GSM (Global System for Mobile Communications) standard was being set up, the head of Vodafone said, "If we get this right, in a few years we could have six million customers globally."

Rivers quipped, "How wrong can you be?"

Check out eWEEK.com's VOIP & Telephony Center at http://voip.eweek.com for the latest news, views and analysis on voice over IP and telephony.