NPR's Dan Charles reports on a new telephone technology called Iridium. The system, which cost over five billion dollars to build, uses a network of satellites to provide complete global coverage. Critics doubt whether the costly system can provide reliable service. Iridium is still under development and is now being field tested by some government agencies and multi-national companies. (7:24) THIS IS PART ONE. PART TWO OF THIS REPORT WILL AIR TOMORROW.