Iridium

The Iridium PTT service has been used by the military for years, but is now cleared for civilian use. Today anyone can stay connected with other PTT phones anywhere on the planet at the touch of a button.  Since PTT functionality is built into Iridium Extreme Phones, they can also be used as a standard satellite telephones.

The Iridium system is a satellite-based, wireless personal communications network providing a robust suite of voice and data features all over the globe. It is comprised of three principal components — the satellite network, the ground network and the Iridium subscriber products, including phones and data modems.

The design of the Iridium network allows voice and data messages to be routed anywhere in the world. Voice and data calls are relayed from one satellite to another until they reach the satellite above the Iridium handset or terminal and the signal is relayed back to Earth. When an Iridium customer places a call from a handset or terminal, it connects to whatever satellite happens to be overhead, and is relayed among satellites around the globe to whatever satellite is above the appropriate Earth gateway, which downlinks the call and transfers it to the global public voice network or Internet so that it reaches the recipient.