I need a php application for pc to pc voice calling.
Try to use locally hosted source code and voip framework. If that doesn't work out at all then you can consider a hosted voip solution.
I just need pc to pc voip calling and hence a 100% free solution. No third party fees/subscriptions.
I'm a developer myself and I know, there are many source codes & Frameworks freely available.
If you already have a demo available, post its link in reply.
The application should be such that I can integrate it in my existing PHP application.