Google keeps chipping away at telco-functionality, quite aptly one service release at a time. Up today: Google Voice will now work with user’s existing mobile (and only mobile) telephone 
number, bringing the service’s voice mail features to the number they already own and use. Since Google Voice is free anyway, users get the best of its features without having to change their number — bingo, quasi number portability. Via a simple set-up screen that helps users forward their missed calls over to Google, a user’s carrier voice mail is simply switched out for Google.
The Google Voice Mail capability is available as an option. Users can still opt to have a Google Voice number and pass that out as their reach-all-my-phones new number. Or they can go the other route and simply append Google Voice to their existing service. Finally, Google is apparently working on truer number portability, allowing a user to port their existing number over to the service–but that’s not ready yet.
For now, Google is letting users forward calls from their regular line into Google Voice’s email service. What you get: speech-to-text transcriptions, visual voice mail, multiple voice mail messages, etc. But set up in this way, you don’t get the ability to ring all your phones at once (follow-me calling) or record incoming calls, among other features. Here’s a full list of what you get/don’t get with this new feature.