I've been very happy with my OpenMoko FreeRunner for about 10 years now. It's running Debian (QtMoko), can send and receive calls and SMS, has WiFi, a Web browser, games, text editor, etc. I can also do anything from the terminal (locally via a terminal program, or remotely via SSH), including "apt-get" from the standard (although outdated) Debian repos.
My only annoyance is that the old QtMoko on-screen keyboard had really good predictive text, but it got removed in an update (apparently it only worked well in English and German; but that didn't bother me as I only know English)