Custom TSP: Quit And Restart Phone Dialer

I have an issue with a custom TSP written in C++. It should be used by outlook to make a call. It works fine under windows xp, but under Vista it doesn't. I am not sure which is the problem because I am able to add it in the Advanced tab from Phone and Modem options and I am able to select it from the New Call dialog from Outlook to use it as a line. When I press Start call i receive an error "An internal error occurred in the automatic phone dialer. Close the dial phone box and then open it again". Also, using the dialer.exe application from microsoft I am unable to use it. The following error shows: "An internal error occured in Phone Dialer. Quit and restart Phone Dialer."