Most people have a Google account of some sort, whether Gmail, Google+, or YouTube. Which means they have ready access to Google Voice and Hangouts, and don't know or care that it can do VoIP as well as Skype can, just nobody uses it.
![tongue :P](https://www.donationcoder.com/forum/Smileys/fun/tongue.gif)
Shows you the power of branding, eh?
As far as alternatives and quality go, if you can convince your friends to use a different client, most
any app using SIP can work as well as a land-line phone depending on your internet traffic, but all parties have to sign up with a SIP provider,
of which there are many free options. For group conversations,
Mumble works very well, and the setup is minimal.