No VoIP (yet at least), the audio is handled entirely by the SIM800 at present. The SIM800 is hooked up via the Pi's UART for commands. Not sure about the SMS

No VoIP (yet at least), the audio is handled entirely by the SIM800 at present. The SIM800 is hooked up via the Pi's UART for commands. Not sure about the SMS software, someone on Reddit asked about that too.