Snom300/Firmware Update Wizard

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1. My snom300 is running a firmware version 7.X (below 7.1.33).
   • I would like to update to the latest released Version 7.1.33.
   • I would like to downgrade to Version 6.5.13.
2. My snom300 is running a firmware version 6.X (below 6.5.17).
   • I would like to update to the latest released Version 6.5.17.
   • I would like to update to the latest released Version 7.1.33.
3. I don't know which firmware version is installed on my snom300. Where can I find this information?
4. Where can I find release notes and download links to older firmware releases?
5. Where can I download the source code of components licensed under GPL? and where can I find the original GPL license text?