We never thought we'd be writing about Google Voice on the iPhone without reporting grim casualty figures from the battle that must have ensued for the companies to get to that point, but turns out Google doesn't really need to go through Apple. Turns out, Google could just make its own backdoor.
That backdoor comes in the shape of a mobile web app that adds most of Google Voice's functionality to the iPhone and Palm's Pre and Pixi handsets. It doesn't have all the bells-and-whistles that you'd enjoy on a Android phone or a Blackberry by way of a dedicated app, but it comes close.
From PC World:
This new version, like mobile Gmail, is among the most app-like browser services I've ever seen, period, letting you dial from your Google contacts list or a keypad, read and listen to messages, send text messages, and configure the app right within mobile Safari. When you make calls using it, the person who answers sees your Google Voice number, not the "real" one associated with your phone: Google makes an outgoing call from the iPhone, then reroutes it over a line of its own.
As you'd imagine, it takes a little work to get Google Voice and the iPhone to get along. For one thing, it can't pull your contacts in locally, so you have to use Google Sync to retrieve your calling list. Also, when you make a call, it doesn't show your phone number but rather Google's routing number for the call — so expect a lot of people not to pick up.
So, Google Voice is finally on the iPhone, but not in the way we — and Google, no doubt — would like to see it.