Satellite phone service Iridium has announced plans for 81 satellites that'll form its next-generation mobile phone service. It already supports more than 359,000 subscribers on its existing sat-phone network. The new service, called Iridium NEXT, was first revealed in 2007. It'll have 72 satellites in space and an additional nine spares on the ground.
This new announcement has confirmed the cost of the project - approximately $2.9 billion - and also reveals that the satellites will be built by Thales Alenia Space. They're expected to be launched from early 2015.