As you fumble through all the different apps on Apple's App Store, you'll come across a number of Voice over IP (VoIP) apps for your smartphone. Some of the most obvious ones are Skype (News - Alert) and Viber. There are also a number of less obvious apps on the market, each offering a unique new way of making VoIP calls.

But perhaps you didn't expect one that lets you make these calls for free. You'd probably have to do a double-take after reading this, but Orange Libon does just this.

Orange Libon is an app for the iPhone (News - Alert), iPad and iPod that allows you to make free calls over the Web to other people in more than 90 countries. The calls can be initiated on practically any network, whether it’s a dinosaur like 3G, a wireless networking medium like Wi-Fi, and 4G.

At this time, though, you still can't use it on EE's 4G network in the U.K.

Aside from calling people through voice, you can also send SMS messages to anyone else using Libon.

Perhaps one of the coolest features that might appeal to business users and professionals is the fact that Libon also transcribes your voicemail into text. Your mailbox also includes a number of other personalization features that allow it to serve as a powerful tool for when you can't take calls.

Orange (News - Alert) has made its app completely free, no strings attached. The reason: Orange hopes to upsell you its premium service that allows you to save conversations, voicemail and your call history in an unlimited storage capacity. Along with this, the premium service allows you 60 minutes of international mobile and landline calling in 31 different countries.

The premium service, known as Libon Premium, will cost you around 2 GBP (~$3.20) per month.

The app is currently available only for iOS in the App Store, and can be used within any carrier besides Orange.

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