I live abroad and use Skype to call home. I tried Internetcalls.com as they
claim to provide 300 free minutes per week.

My parents phone line is connected to a fax/answering machine and when a call comes in, it checks if it is a voice call or a fax call. After this
check there is a different ringtone. At this point Internetcalls.com cuts me
off.

I also noticed that as soon as a "normal" answering machine picks up, I get disconnected and can't leave a message. Is this is normal with
Internetcalls.com? Or just with the free calls?

I never have this problem when using Skype.