Why does the display on my RST970 Handset lock up, or goes blank?

There is a known problem (acknowledged by Iridium) that when SMS messages are being delivered AND the user is simultaneously reading or replying to existing messages (via the handset), the phone may lock up.  The only way the display can be restored is by recycling power to the device.  

• Iridium 9575 Extreme Handset firmware HL15002 fixed this issue.
• Iridium 9555 Handset firmware HT15002 fixed this issue.
• 9522 Transceiver ST15001 fixed this issue.
  (Applicable only to Beam-Iridium Docking stations/terminals)

NOTE: When handset display lockup occurs, this will not affect any other functionality of the device, and Voice calls via the RJ11 port (if applicable), and also ‘Comm Port / USB ' data calls are still possible.