See http://msdn.microsoft.com/en-us/library/bbx34a2h(VS.100).aspx
Add the following sections in the forever4035.exe.config file :
<startup useLegacyV2RuntimeActivationPolicy="true">
<supportedRuntime version="v1.1.4322"/>
<supportedRuntime version="v2.0.50727"/>
<supportedRuntime version="v4.0" />
</startup>
Forever4035 is fully compatible with all VMware flavours as well as Windows XP mode.
Note however that only a single instance of the forever4035 softphone can be executed on a single physical machine as it requires the exclusive use of the sound card.
Execute the forever4035 setup program as Administrator in Windows XP compatibility mode
Make sure the microphone is activated in the sound card driver otherwise the program will crash (this may require you to plug a physical microphone).
See http://msdn.microsoft.com/en-us/library/ms973190.aspx
Use the attached Corflag.exe tool to force execution on the WOW64 subsystem (Windows 32bits Over Windows 64bits):
corflag.exe /32BIT+ /Force forever4035.exe