This new firmware is 5.6.1.
You can download the new firmware update at the Inmarsat support site.
Back in January, Inmarsat released news that any IsatPhone Pro that hadn't upgraded to firmware version 5.3.0 or above would cease to work with the new network improvements scheduled for later this year.
Firmware version 5.6.1 supersedes the mandatory firmware versions 5.3.0 and 5.5.1 that were released recently.
The operational changes to the network are currently scheduled for November 28th, 2014, so make sure you upgrade your firmware soon if you still have an older firmware running on your IsatPhone Pro - otherwise you could find yourself without a working satellite phone.
You can check if you have the latest version on your IsatPhone Pro, by going to Menu > Settings > About > Firmware version.
Please note that the Inmarsat firmware update tool is for Windows systems only. Please contact us for information regarding upgrading on Mac or Linux machines.