On Konftel 300IP or Konftel 300IPx

1. Restore the firmware on the phone by pressing and holding the MENU button during boot up of the phone. 

A rescue menu will appear and you should select "3. Restore firmware"

2. After the phone has booted, go to the web interface and login in as "Admin". 

Go to Provisioning and upgrade the Konftel with this file: http://www.konftel.com/Download/konftel_300ip/KT300IP_UPGRADE_FIX.kt

3. After the phone has done a successful upgrade it will reboot.

4. When the phone starts again, go to the Provisioning tab and do a normal upgrade to the latest version