Google Voice, now rolling out to the general public, is a generally excellent service. The major drawback is that you must "socialize" a new phone number. But once you do it can be your "number for life," with other phone numbers rotating behind it. Now the full range of Google Voice's capabilities have been brought to mobile -- Android and BlackBerry devices at least. An iPhone app is awaiting Apple approval.

I wrote about the service and the implications of the new Google Voice mobile app on Search Engine Land. 

Essentially the mobile app allows users to send SMS messages and make phone calls from their mobile phones using the Google Voice number. Those on the receiving end of the call see the Google Voice number on caller ID, not the underlying wireless carrier number. Users need only have a data plan -- though data-only plans aren't available from carriers -- to make calls and send texts, as well as use the mobile Internet. Thus Google becomes the brand that the user interacts with and the carrier is the provider of the commodity service (i.e., connectivity) in the background. 

There are some potentially dramatic pricing implications for carriers here and if they "break ranks" it could represent a problem for their long term voice revenues. 

The only requirement of Google Voice for mobile is that the handset in use be compatible with the app. The features of Google Voice make it highly desirable from a consumer and small business standpoint. If consumers can understand it, more of them will adopt it. And carriers won't like it. 

This is a stronger consumer proposition than Skype or Truphone for end users because there's a viable phone number that gets used and exposed. Also the range of features is broader and richer.