Palm Inc., handheld computer and phone maker, will unveil a new version of its Treo smart-phone next month, striving to revive sales amid tough competition.

The Californian-based firm said in July the new version will operate on Vodafone's high-speed third generation (3G) network and be powered by Microsoft Corp.'s Windows Mobile operating system.

Palm is to launch the new handset to Vodafone customers in a number of European countries including the U.K., Germany, Spain, Italy and Netherlands as it attempts to win back the confidence of a market it once dominated with its Palm Pilot device.

The company is severing ties with its former operating systems partner, Palm Source, and using rival's Microsoft's Windows based system instead.

The announcement is going to be made in the UK on September 12, and we will give all the details then but at the moment all we are saying is that it will be out before the end of the year, said a Palm spokeswoman.

In June, the company stopped shipping its Treo 650 model in Europe because it was not compatible with a newly introduced phone technology standard.