Register custom Windows 10 callto: uri handler

I am trying to register a custom callto: uri handler on Windows 10. I followed the instructions below: https://msdn.microsoft.com/en-us/library/aa767914(v=vs.85).aspx

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\callto]
@="URL:callto"
"URL Protocol"=""

[HKEY_CLASSES_ROOT\callto\shell]

[HKEY_CLASSES_ROOT\callto\shell\open]

[HKEY_CLASSES_ROOT\callto\shell\open\command]
@="\"C:\\Users\\Michael\\AppData\\Roaming\\someFolder\\some.exe\" \"%1%\""

      

        
        
        
      

    

It works like a charm under Windows 7, but refuses to work under window 10. If I click on the callto link in any browser, Windows will ask me to select an application to open the link.

Any hints are greatly appreciated.

peggel