Allowing smart phones (and tablets) to receive mobile phone coverage anywhere in the world.
This means calls and texts.
That it also allows internet connectivity is a bonus. Next Gen will increase internet speeds, but global internet connectivity is not its main USP.
The breadth of mobile phone coverage is the best on the market. You want to make 100% sure your smartphone can make calls and texts outside of network mobile phone range, you buy buy Iridium GO!
As Imrahn said it is effectively a "portable mobile phone tower".
The fact that it can offer connectivity to 5 devices at a time is also a USP (I believe, their may be others that allow multiple devices to connect to a single "portable mobile phone tower".
Saying it converts smartphones to satellite phones is a simple catchphrase I use so that anyone immediately understands the capabilities and benefits.
WRR Price at posting:
13.0¢ Sentiment: Buy Disclosure: Held