The popular Google Voice standalone app hasn’t yet been approved to App Store for iPhone, iPhone 3G or iPhone 3GS users to legally download to the mobile phone device. But Google is determined to allow iPhone owners to enjoy the free Google Voice service via backdoor web browser access, and has released updated Google Voice web app for iPhone and Palm WebOS, accessible via phone’s browser.

Google Voice provides a U.S. phone number free of charge to the user, which can be used to receive inbound calls that are subsequently forwarded to other phone numbers of the subscriber. Most importantly, Google Voice users can dial and place outbound calls to domestic and international destinations, where calls to United States of America (including Alaska and Hawaii) and Canada is free of charge, effectively shortchange the exorbitant charge imposed by mobile carrier or telecommunication service provider on voice calls.

The new updated version of web-based Google Voice is a HTML5 web application, instead of typical browser-based service. According to Google Voice blog, Google Voice features AppCache that lets users interact with web apps without a network connection and local databases allow users to store data locally on the device, so users don’t lose data even after closing and exiting the browser. With the new web app, technology, it does not compromise the features a standalone app, and Google Voice can now run perfectly in iPhone, Palm Pre, Palm Pixi, Palm Pre Plus, Palm Pixi Plus, and most other smartphone and mobile phone devices with modern HTML5 enabled mobile web browser, in similar performance and speed of a native app.

With Google Voice web app, user can dial phone numbers on an interactive on-screen keypad to make calls from the phone, including iPhone, that show user’s Google Voice number as the caller ID. Google Voice user can also listen to voicemail and read voicemail transcripts, send and receive text messages for free, and take advantage of the low international call rates offered by Google Voice from within the browser, as shown in video demo below.

With Google Voice web app, there is nothing to download or install on the phone. Users who want to access Google Voice on the mobile devices simply has to point the mobile browser to visit the following URL link location, and then sign in to Google Voice account.

User who prefers standalone Google Voice app, and uses a jail-broken iPhone, can try out GV Mobile + instead.

Update: Official Google Voice for iPhone