I have an Asus netbook with Windows 8. VoipConnect dials and connects to any number. I can hear the other party, but cannot be heard. The mic bar on the VoipConnect window indicates no sound. In the Options tab Sound Device is correct. At the same time Skype works perfectly (with exactly the same sound setting). It must be therefore some software problem. I use VoipConnect 4.13 built 738 which is the latest. The same version works perfectly on my desktop with Windows 7.
Try to use one application at a time and update VoipConnect to latest version. It's possible that one of the applications requires exclusive access to MIC port making it unavailable for the other one.