Google Inc. is trying to make its Voice application easier to use on the iPhone, whether Apple Inc. likes it or not.

In an upgrade announced Tuesday, Google revised the mobile Web site for Voice so that it's easier to display the service's most popular features on the iPhone's latest operating system.

Among other things, Voice offers an alternative dialing pad, voice mail and international calling discounts.

Apple has refused to allow the Voice program to be distributed through the iPhone's applications store since last summer on grounds that it would duplicate or alter important iPhone features. To get around that roadblock, Google is trying to entice iPhone users to rely on a mobile Web browser to access Voice.

Google says the overhaul will make the Web browser experience more like what users would get if Google were allowed to offer a downloadable app that could be installed on the iPhone.

Google already offers downloadable Voice apps for Research In Motion Ltd.'s BlackBerry phones and devices running on Android, an operating system developed by Google. The upgrade to the mobile Web site also makes Voice simpler to use on devices that run on Palm Inc.'s operating system.

The jousting over the Voice application underscores the rising tensions between Google and Apple, the two most valuable companies in Silicon Valley.

Apple's rebuff of Google's Voice application triggered a Federal Communications Commission inquiry into whether Apple and AT&T Inc., the iPhone's exclusive U.S. service provider, were trying to stifle potential competition.

Apple told the FCC that it hasn't rejected the Voice application outright, but Google says it still hasn't heard anything further on its attempts to make the program available for iPhone downloading. AT&T says it didn't take part in Apple's review of the Voice application.

Google's Voice service had 1.4 million users as of October, according to a company disclosure to the FCC.