When you dial a number, Google Voice simply makes a call to your iPhone while simultaneously calling the number of the person you are trying to reach, so you still pay for the voice minutes. But the appeal of having Google Voice on your iPhone is the ability to read transcribed voicemails, or play them, and avoid SMS charges by texting through Google Voice. It even offers offline caching and takes advantage of the HTML5 features of mobile Safari. But all these things are not completely compatible with the phone browser from now on.

The downside is that it cannot access your contact list on your iPhone through the browser. Although, VoiceCentral mimics the look and feel of the iPhone contact manager, you have to export your contacts to Google Voice first and access them that way. Another limitation is that the audio plays through the speaker instead of through the earpiece, but if you are using a pair of earphones that is not a problem.

Google Voice uses a carrier’s existing network to place calls: so it’s not like you’re getting around your monthly allotment of minutes by using the service as a voice over Internet Protocol, or VoIP phone. Still, Apple has approved Skype for the iPhone, so it’s a little unclear what might be the sticking point, especially since Google has been given preferential App Store treatment in the past.

I don’t think these numbers are really surprising. Even though Apple really doesn’t want us to, it is giving us more and more reasons to jailbreak and finally get access to applications or features that are not allowed in the App Store.