Three owners of Palm's Treo 600 and 650 hybrid phone/ PDAs (personal digital assistants) have filed a lawsuit claiming the devices are inherently defective. They are seeking an injunction barring the sale of the devices.

The three owners, Mario Palza, Charles Boulais, and Nissa Gay, claim that their Treo 600 and 650 devices suffer from a host of problems such as the quality of phone calls and the stability of the software on the device. Last Friday they filed a complaint with the Superior Court for the State of California seeking damages and a recall of the Treos.

The owners claim that phone calls placed by the Treo 600 were indecipherable because of the poor quality of the phone's speakers and choppy delivery of the user's voice, according to the complaint. Gay cited problems with the Treo 650's software, claiming the device crashed up to 10 times a day.

The plaintiffs believe these problems afflict numerous Treo owners and are attributable to Palm, not the mobile networks that sell the device, said Ira Rothken, an attorney representing the group, in an interview on Wednesday. Each of the owners attempted to resolve their issues through Palm's customer support office, but they claim that Palm would replace their Treos with equally defective models, Rothken said.

A Palm spokeswoman did not immediately return a call seeking comment on the lawsuit.

In essence Palm has reorganised its operations around the Treo. Sales of traditional PDAs have plummeted in recent years as mobile phones have grown more sophisticated and capable of handling the basic contacts and appointment calendar software that first brought Palm Pilots to prominence.

However, shipments of devices such as the Treos, HP's iPaq h6300 models, or Research In Motion's BlackBerry 7100 are growing as users gravitate toward handhelds that combine the processing power of a PDA with the ability to make phone calls.

Palm is expected to have shipped about 480,000 Treo devices in the company's first financial quarter, which ended in August, said Todd Kort, principal analyst with Gartner. About 90 percent of those shipments are of the Treo 650, which was first introduced in October of last year. The Treo 600 made its debut in 2003 from Handspring, which was later acquired by Palm.

No manufacturer is immune to problems with computer hardware, but the Treo has been a success for Palm and mobile networks over the first few years of its life, Kort said. If the problems with the device were as widespread as the owners claim, it's likely that mobile networks would have stopped selling the device after receiving complaints, as T-Mobile US did earlier this year with HP's h6315, he said.