The next generation of portable wireless Internet access is available in Seattle through a Clearwire trial service.

Clearwire, the wireless broadband operator, has quietly begun selling PC cards and a new service that lets users access the Internet wirelessly around Seattle. Most WiMax services, including Clearwire's in other U.S. and European cities, require larger modems that must be plugged into a power outlet, making it difficult for users to carry the modem to various locations for access. The new PC card lets customers connect to the wireless network easily from laptops at cafes or elsewhere in the coverage area.

Anyone can visit a Clearwire store in the Seattle area and sign up for the portable service, said Helen Chung, a Clearwire spokeswoman. After rebates, the PC card, which is made by Motorola, costs $80. Monthly service costs $60 and offers 1.5Mbps download speed.

The Clearwire trial service competes with mobile cellular offerings. Verizon Wireless, for example, offers a PC card for mobile data access for $60 per month with an average download speed of 600Kbps to 1.4Mbps. However, Verizon's service prohibits continuous downloading or streaming of audio and video, and some customers have complained of having their accounts cancelled for overuse. As a result, some customers subscribe to such cellular services for mobile use and also subscribe to a wired broadband connection for use in their homes or offices.

The Clearwire service doesn't come with any download limits, Chung said, so it could be used as a customer's only broadband connection.

The cellular operators have an advantage, however, in that customers can use the services while mobile, such as when traveling on a train or in a car. The current Clearwire service is not designed to support connections while the user is moving.

Chung couldn't say how many customers are using the service. She also cautioned that the service is a trial and so it's unclear what it might cost in the future.

In May, Clearwire announced that the U.S. Federal Communications Commission had approved a Motorola PC card that the operator planned to use. At the time, Clearwire said the card would be available in its markets during the second half of the year. That same month, Clearwire said that along with Intel and Motorola it had completed a trial of a mobile WiMax service in a Portland, Oregon, suburb. Clearwire said it hoped to make that service available in 2008.

Sprint Nextel Corp. is also in the process of building a mobile WiMax network, expected to launch next year.

Clearwire currently offers its fixed service in 16 U.S. states as well as five international markets.