I would like to initiate a call with the react-native api and play a ringtone on the receiving phone. Is this supported on the api?
You can check out this library: https://github.com/react-native-webrtc/react-native-callkeep
It uses callkit on the ios side and connection service on the android side.
We also have some sample apps for IOS and Android that use CallKit and ConnectionService respectively and use Agora RTM. You can find them here: https://github.com/AgoraIO/Advanced-Video/tree/dev/backup/Calling-Interface