London's hotspots unfit for voice

Two-thirds won't give you a decent line

Most of London's wireless hotspots can't support more than one voice-over-IP call at a time, according to a survey by WLAN analysis specialist AirMagnet.

The company surveyed 15 hotspots around Oxford Street and the City last month. It said that 11 of them suffered from coverage problems that prevented multiple simultaneous voice-over-Wi-Fi calls.

AirMagnet boss Ian Schenkel said that without remedial work, people trying to use Wi-Fi or dual-mode phones could suffer dropped or poor quality calls, and might simply give up trying to use it as an alternative to their current phone service.

"The hotspots were OK for data use," he said, "but network usage is evolving, and now the infrastructure needs to evolve to keep up."

He said the most common problem was being on the same channel as a neighbouring network, while other hotspots suffered interference from Bluetooth phones or - especially in sites also serving food - from a microwave oven.

Most interference issues can easily be fixed by a site survey, using a portable PC and WLAN analysis software, and adding extra access points if needed, he claimed. He acknowledged that a thorough survey takes time -that's why AirMagnet only checked 15 sites, but added that he believed it was a representative sample.

"It's much more three-dimensional than just adding more access points," he said. He pointed out that while metal air conditioning ducts will block radio signals, glass can reflect them.

"The best place we found was a phonebox with BT OpenZone," he said. "It was very well set up - it's somewhat ironic, given that it's a phonebox and we were testing voice-over-Wi-Fi."®

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