The more, the merrier. That's the motto of a new roaming service from T-Systems International, a unit of Deutsche Telekom, which is targeting wireless providers worldwide.

T-Systems is linking thousands of wireless LAN (WLAN) hotspots into one virtual network, allowing users to access any network regardless of their home provider, said T-Systems product manager Christian Wollner. It has already signed up 120 international partners for a total of 10,000 hotspots.

"The more operators we can connect, the easier it is to attract new ones, and the wider the coverage is for users," Wollner said.

Industry analysts say roaming will be key to improving the Wi-Fi situation, where users currently can't be sure that their service will give them access to any hotspot that might be nearby. However, competition among roaming providers and aggregators means that there is still no single industry-standard system for roaming, said Disruptive Analysis founder Dean Bubley.

Even when WLAN access aggregation is sorted out, these services face the even more complicated issue of combining their WLAN access with emerging 3G services which address the same market but with different coverage and bandwidth (How complicated is this? Read our analysis of this problem).

The roaming service is ideal for business travelers who seek high-speed wireless Net access without the hassle of having to sign up and pay separately every time they log on to a hotspot of another service provider. The service, he said, is similar to the international roaming agreements between mobile phone companies, allowing customers to make calls on networks outside their own.

For its part, T-Systems remains invisible to end users. "We are providing a wholesale roaming service," Wollner said. "We don't sell directly to corporations or consumers but rather to mobile phone operators, hotspot operators and other telecommunications service providers, which can market the service as they please."

The business model works like this: T-System buys access to hotspots from so-called wireless Internet service providers (WISPs) and resells this access to online companies, mobile operators and other WISPs seeking to extend their coverage. The German company clears traffic between its partners and handles internal billing.

But even if the T-Systems brand name isn't visible to Wi-Fi users, the value proposition of its roaming service is difficult to overlook, according to Wollner. "Users want things to be easy," he said. "That's what this is all about."

Travellers logging onto a foreign Wi-Fi hotspot find a list containing their home provider. After clicking on their provider, they are redirected to that operator's website to log on with their name and password. "Travellers don't need to worry about multiple passwords or payment and by being directed back to their home provider, they also don't need to worry about foreign languages," Wollner said.

The system works thanks to T-Systems' support of state-of-the-art authentication, authorisation and accounting interfaces.

T-Systems isn't the only company trying to grab a share of the emerging Wi-Fi roaming market. It joins a highly competitive group of aggregators, including iPass and Intel spin-off RoamPoint, which are seeking as many hotspots as possible to increase the attractiveness of their roaming service.

The good news: those numbers are steadily growing. The number of public hotspots worldwide is expected to rise to 135,000 by end of 2006 from 35,000 at the end of last year, according to estimates from Datamonitor.

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