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.
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.