The train was on time, but the commercial launch of Wi-Fi Internet access service on high-speed trains between Brussels and Paris was marred by a technical glitch that kept many travelers offline for much of the inaugural journey.

Train operator Thalys is installing Wi-Fi access points on its high-speed trains running between Paris, Brussels, Amsterdam and the German city of Cologne to connect travelers to the Internet via a satellite link or 3G (third generation) mobile networks while the train is moving, or to Wi-Fi hotspots in stations along the route.

But for the senior executives of the train operator and the system's developers gathered on board the 1:13 p.m. departure from Brussels for the commercial launch of the service on Wednesday, pride quickly turned to dismay as they realized that dozens of journalists invited to test the service were unable to log in.

As technicians attempted to restore service, Henry Hyde-Thomson, founder and chairman of 21Net, the company behind the technology, said the satellite link was still working but that the problem was with the on-board equipment.

"The DHCP server has given up for some reason," he said, referring to the system that hands computers the IP (Internet Protocol) addresses they need to use the system.

When working, ThalysNet allows first-class passengers to create an account and connect to the Internet free. Passengers in second class can access an on-board portal offering travel information and ticket reservations for free, but Internet access costs ¬6.50 (US$10) an hour, or ¬13 for the full journey. The trip from Paris to Brussels takes only one hour and 20 minutes, but the journey to Cologne is over three hours long.

By journey's end, the server was working and it was possible to search Google and see the news headlines on CNN.com.

Jean-Michel Dancoisne, CEO of train operator Thalys, sees broadband Internet access quickly becoming a basic need among business travelers. The ability to deliver it will be a major differentiator between rail and air travel, he said.

ThalysNet is managed for Thalys by a consortium of three companies: 21Net, which developed the satellite communications system for high-speed trains; Nokia Siemens Networks, which supplies some of the equipment and installs and integrates the systems on the trains, and Telenet, a Belgian Internet service provider and hotspot operator, which provides the billing and authentication system.

So far, seven of Thalys' 26 trains have been fully equipped for Wi-Fi: Paul Broekhuizen, head of the consortium, expects to have work on all 26 trains completed by October.

Signals are bounced off a satellite over the Atlantic Ocean and down to a base station in Spain. The company currently allocates around 2M bits per second to each train -- although with compression, that looks more like 4M bps to users, said Hyde-Thomson.

There are no plans yet to shape or block particular kinds of traffic, and unlike many mobile phone operators, ThalysNet allows video streaming and voice-over-IP calls. The only restriction is that access to certain Web sites carrying adult content is not allowed, said Ines Clenjans, business manager for Wi-Fi on trains at Nokia Siemens Networks.

For now, the Wi-Fi-enabled trains are easy to spot: in addition to the "Wi-Fi inside" stickers in every window, they have a large white radome on top, protecting a satellite dish 80 centimeters in diameter and 72 cm high. The dish is motorized to keep it pointed at the satellite, however the train turns. 21Net is seeking certification for a lower-profile dish that is oval in shape and just 45 cm high, said company spokesman Philip Haines.

In the future, the company hopes to use a phased-array antenna just 3 cm thick, "covering as much of the train's roof as we can," said Haines. Phased-array antennas are composed of many flat elements which each transmit the same signal at different times to direct the beam. Picture a "Mexican wave" in the crowd at a football match, where each person in the crowd jumping up and down creates the impression of a wave moving around the stadium. The wave can be sent in another direction by changing the order in which people jump. With a phased-array antenna 21net hopes to do away with moving parts and bulky covers.