I am working on a soft phone project. In this project I want to use the VoIP Development Kit. But I don't know how to add this library to my QtSDK. Anyone can help me in this issue? To be specific I put that library in my SDK in different locations. But all the it gives the same error that VDKQtengine was declared with no type. What is the procedure to add this kit to my SDK? Do I have to call it in the project file? If so, then how could be it done?