One analyst said the number companies preparing to show off their wares at the GSMA Mobile World Congress in Barcelona amounts to “a small but symbolic step” forward for the Internet search and advertising giant, which has set it sights on the nascent but potentially lucrative mobile ad market.

“Having prototypes is a signal, but not a promise, that the phones will be out there,” said Bill Hughes, analyst at In-Stat consultancy.

Hughes said the success of Google’s effort to develop a next-generation mobile phone will largely depend on convincing independent developers – whom Google is counting on to add all the bells and whistles to its mobile phone software – that there will be a broad market for their applications.

Without evidence that the Android project has momentum, developers will be unlikely to spend time designing applications for Google’s mobile software.

Google is hoping its mobile phone initiative will one day enable wireless subscribers to easily surf the Internet without restrictions – and allow advertisers to reach consumers through their handsets.

Google declined to comment on a recent report that it planned show off a prototype of its own so-called “Gphone” next week, but a spokesman noted the company has been working with a number of partners to develop handset prototypes.

“We’re very excited about the momentum building behind the platform as demonstrated by the number of companies that are supporting it with their technology,” the spokesman said.

One prototype will belong to ARM Holdings PLC (ARM), a British company that develops architectural designs for chips and sells them to semiconductor manufacturers such Texas Instruments Inc. (TXN), NEC Corp. (6701.TO) and Samsung Electronics Co. (005930.SE).