I need an expert in VoIP technology

I need a service like the one offered on this site - [login to view URL] I wanted to sign up for their service but they do not return my mails then I read somewhere that I can do it simply on my laptop. So I need someone to tell me the hardware required and the also provide the software. Here are the references [login to view URL] [login to view URL] [login to view URL] The extra features like voice change are not necessary