This project contains a basic (absolute minimum) set of config files for installing Asterisk on a Raspberry Pi.
It also contains the pre-compiled binary file for the opus codec for Asterisk 13. (codec_opus_arm.so). It is built for use with the Raspberry Pi (Arm CPU).
To use it, simply copy to the /usr/lib64/asterisk/modules/ directory.
Also see the video for the full details: https://www.youtube.com/watch?v=52sEPVPV9JE