Iridium has released new firmware updates to its 9555, Extreme (9575) and Extreme PTT handsets:
Iridium 9555 - HT17001
Iridium Extreme (9575) - HL17001
Iridium Extreme PTT - HP17002
The updates include bug fixes and new features. While these releases are not mandatory, Iridium recommends that the handsets are upgraded as soon as possible to provide the best service available.