Its "bent-pipe" satellites function as simple relays between end-users and ground stations.Call processing and switching are carried out by gateways on the ground.
Some of its initial areas will be Argentina and South Africa.
Also different is Globalstar's use of Earth-based telecoms networks.
It means, unlike conventional mobile phones, that Iridium won't work indoors.
Worse, dropped calls are common, completion rates low, while other network functions perform unevenly.
Worse still, the Iridium handsets were clunky, weighed about 1lb, and harkened back to Motorola's infamous brick phones, common a decade ago. Indeed, nine months after its highly publicised launch and a pounds 60m international marketing campaign, Iridium had managed to attract less than 20,000 customers compared with a guarantee of 52,000 specified in lending covenants with a syndicate of bankers that includes Barclays and Royal Bank of Scotland.
Though lots of new products fail to match early expectations, few, it seems, have failed with such an international bang.But the most damning indictment of Iridium, and of Motorola, its largest shareholder with an 18 per cent stake, must be the system's patchy technology.Handsets depend on strict line-of-sight access between the phone's antennae and the orbiting satellite.As one analyst said: "If Globalstar doesn't go, no one will." But even if Globalstar fails, another generation of satellite services, this time targeting the burgeoning market for Internet access, are on the drawing boards for launch from 2003.Their strategy is to offer sizzlingly fast Internet service at speeds of more than 2.0 megabits per second - 50 times existing modem speeds.Analysts believe the market could reach pounds 10bn by 2005 with 30 million customers.