The final pieces in the Iridium puzzle will be put into place on Sunday, when project officials push the blast-off button on a Delta II that will carry the system's last five satellites into orbit.

Iridium bids to be the first global satellite-communications network, promising users the chance to send and receive calls and pages no matter where in the world they happen to be standing. Typically, users have to deal with dropped calls or different communications protocols (and the need for a different phone) as they travel the globe.

By blanketing the earth with a network of satellites in low-earth orbit (240 miles above Earth), Iridium officials believe the system can provide high-speed, global communications through a single phone. The catch is, users will have to have an Iridium phone.

After testing and putting final links into place for the network throughout the summer, Iridium officials plan to open the system for service in September.

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