I get GSM quality calls on my Nexus 4 (at minimum) via cSIPsimple, pbxes.org, and Google Voice, usually over a mediocre repeated WiFi connection. If there's interest, I'll write it up.
Mild configuration hassle but reliable. Helps to move Google Voice to an account where where you never IM.
Mild configuration hassle but reliable. Helps to move Google Voice to an account where where you never IM.