IsatPhone PRO current firmware: 5.17.2
IMPORTANT! If your IsatPhone PRO satellite phone's firmware version is lower than 5.3.0, your phone will NOT operate properly. You must update to the current firmware in order to use your Inmarsat phone and service.
For users of 5.3.0 or higher this is a recommended upgrade, meaning that the features introduced by the firmware are important but not critical for the service, including the network and the IsatPhone Pro handset. The 5.17.2 update is mandatory only for users covered by the MEAS (I4-F2) satellite region.
To check your phone's firmware version, go to Menu > Settings > About > Firmware version.
You can download the firmware update tool and instructions at Inmarsat website.