• In GRAPE, go to: Phones - Select your device - Settings
  
  
• Search Settings: Firmware
• Under Software update you have the setting Firmware
  
  
• Enter the firmware URL, this you can find on the device software page
  
  Example: https://profile.gigaset.net/device/P710/gigasetP710-10.1.198.162-SIP-r.bin

The next time, the device connects to Grape, the firmware update is started. (Depends also on Firmware update policy setting)