There are 2 repositories under digital-voice topic.
Turn your Android phone into Amateur Radio Codec2/OPUS APRS enabled DV handheld transceiver (Bluetooth/BLE/USB/TCPIP KISS/Sound modem client for DV digital voice communication)
ESP32 based Codec2/OPUS DV hobby UHF 3d printed handheld transceiver aka walkie-talkie
Codec2 low bit rate audio codec Arduino library for ESP32
A wxWidget free port of ircddbGateway with some more (not yet all implemented) features ;)
Converts a .vcf export from Google Contacts into a format that can be imported into a BT Smart Hub 2 for use with BT Digital Voice phones