Microsoft is expected to announce a major revamp of its phone software on Monday, in what analysts see as the last chance for the company to regain its momentum in a market where it's been overshadowed by Google, Apple and others.

CEO Steve Ballmer will be speaking at the world's largest cell phone trade show, in Barcelona, Spain. Analysts expect him to reveal Windows Mobile 7. The software could be in phones by late this year.

The new software comes as Microsoft Corp. has taken a back seat to Research in Motion Ltd.'s BlackBerrys among corporate users, and Apple Inc.'s iPhone among consumers.