Satellite phones are just about one of the coolest communications devices on the planet. No longer are you restricted to being near a mobile phone mast. You can make and receive calls from almost anywhere. The problem, of course, is that it's an expensive business using satellites and out of the reach of most people.

But there's a chance that's going to change over the next few years. And while satellite phones are unlikely to be something everyone needs, it's possible they won't be unaffordably expensive for much longer, at least thanks in part to Thuraya's new product for the iPhone.

It's called the SatSleeve, and we think that's a good name because it describes what's going on here pretty well. You pop your iPhone 4 and 4S - no iPhone 5 support just yet - and it acts as a sort of case, into which is built everything you need to make a satellite call or send a text message.

To connect your iPhone, and make calls, you simply press the bluetooth pairing button on the back of the device, under the battery compartment cover, then search with your iPhone for it. Once you're paired, then you can start using the free Thuraya app to make calls and send text messages. The app tells you when you're in service, and you can access your iPhone's phonebook too.

There's a 2400mAh battery in the SatSleeve too, this powers the satellite calling, but you can also use it to charge your iPhone too. The aerial is solid and quite chunky, but you're communicating with something in space here, so that's to be expected. We're just amazed it doesn't require you to have a satellite dish hat on all the time.

We're told there's a Sleeve coming shortly that will attach to the iPhone 5 shortly. There's also talk of a version for certain Android phones. Thuraya has chosen the iPhone first because it's easy to make the hardware a standard size to fit these handsets, and they're also very popular phones with existing satellite phone subscribers.

The company also says it's working on a Wi-Fi connected version that will allow your iPhone to connect to the internet via its data service. In a good signal area, you should get 0.5mbps over this service, which in some parts of the world is positively lightning-fast.

With Thuraya's two satellites, you can make calls in over half the world. The only place not covered is the Americas, the poles and some of the very most northern parts of Europe and the very lowest bit of South Africa. The system works on a set of frequencies that are quite close to those of GSM services, at 2000MHz. You do need to be outside, realistically, or near an open window with a view of the southern hemisphere - look for a Sky dish, Thuraya's satellite is in a similar direction.

We've got a SatSleeve to review, so we'll be testing it out over the next few weeks, and we'll tell you how it stacks up.