We got news this morning that Apple has approved an iPhone application for Vonage, the popular online phone (Voice over Internet Protocol, or VoIP) service. This means that if you have a Vonage account for your landline at home, you'll be able to make calls with it through your iPhone. That's pretty cool. Sort of.

The killer function, though -- and something that’s missing from similar apps -- would be the ability to make calls over AT&T's 3G network, rather than just over a WiFi network.  But we still don't know yet whether the Vonage app will include such a function, and judging from previous rejections, you shouldn’t get your hopes up.

Let’s recount the ways that Apple and AT&T have restricted VoIP or VoIP-like apps for the iPhone so far:

- Skype. It's a beautiful app that includes almost all the functionality of its desktop cousin. The only problem: You can only make calls over a WiFi connection. If you try to make a call on the 3G data network, you're out of luck. And chances are, where there's WiFi, there's a desktop or laptop computer nearby with Skype already installed. Color me redundant.

- Google Voice and friends. This summer, Apple began pulling Google Voice-related apps from its app store, claiming that they duplicated core functions on the iphone (like phone calls and voicemail). Soon after, the official Google Voice app was blocked (though not rejected, Apple says it's still reviewing new versions of the app). These moves went even further than blocking Skype over 3G -- you can't use any Google Voice-related app on the iPhone, over any sort of Internet connection.

So now Apple and AT&T have an opportunity  to change course with Vonage. Come on, folks, let 'em use 3G. Because otherwise they’re just offering us more crippled service, and there’s nothing here to celebrate.