It made me wonder what's free-er about an ordinary phone call.
You can use any phone that you like to place a call. You can even build your own phone. (Depending on your choice of phone you might have to rely on non-free parts like GSM voice codecs.)
You have the freedom of choosing between multiple service providers, all of which are interoperable. If you want, you can even get access to the underlying SS7 phone network and be your own provider.
Until something like Ekiga does multipart conference calls, a minimum of 10 nodes and more voice only, then it is hard for me to switch from something like Skype.
Me and my buddies recently switched from Skype to Mumble+IRC. Works great, I like this setup way better. The big downside is of course that it requires a server.
Does it become less non-free if somebody else runs the software? Or maybe it shifts the moral burden of using something non-free to somebody else?