Hallo,
Nur mal zum Test vielleicht hilft ja das hier: 
Code:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\AVM\Fritz! 2.0\Fax]
"Cip"=dword:00000004
"CapiController"=dword:00000005
[HKEY_CURRENT_USER\Software\AVM\FRITZ! 2.0\Fax]
"FritzBox"=dword:00000001
"Cip"=dword:00000004
"CapiController"=dword:00000005
"ControllerFax"=dword:00000001
oder x64
Code:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\AVM\Fritz! 2.0\Fax]
"Cip"=dword:00000004
"CapiController"=dword:00000005
[HKEY_CURRENT_USER\Software\AVM\FRITZ! 2.0\Fax]
"FritzBox"=dword:00000001
"Cip"=dword:00000004
"CapiController"=dword:00000005
"ControllerFax"=dword:00000001

Gruß Erwin