If you want to add a web phone to your own page, here doddlephone can help you, all you need is to have a sip account that can make or receive calls.
Here is how:
<iframe src="http://widget.doddlephone.com/embed/webphone.jsp?sipserver=your sip server here&username=your username here&password=your password here&auto=yes"
frameborder="0" width="550" height="398" scrolling="no" ></iframe>
