Iridium is the only Satellite Network with a TRUE GLOBAL coverage, even on the North and South poles. Its network comprises over 70 Low Earth Orbit Satellites. Currently, this network is being upgraded with next gen satellites, all satellites will have been upgraded with the use SpaceX launch vectors by August 2018 to the NEXT(™) Satellite Network (depending on launch and orbital navigation success). Chosign Iridium, means chosing for the newest and the best.
Track Iridium Satellites here: http://www.satflare.com/track.asp?q=iridium
Iridium Coverage Map
Iridium service is 100% global, It does this by using a large number of LEO (Low Earth Orbit) satellites that are moving across the sky at great speed. Your Iridium satellite phone connects with these LEO satellites for communication.
Iridium PTT Service Regions
Iridium PTT is a unique service. PTT stands for Push To Talk. When using PTT, the group of users must determine the area where the phones are going to be used as PTT. PTT phones can also be operated as regular phones; when in regular phone mode no region needs to be determined, they operate in the entire global coverage. Users can determine the areas of use dynamically and in real time via the PTT Command Center web portal. Currently only th Iridium 9575 PTT version can use this service.