I"m not seeing any API call for monitoring calls, whisper, or barge feature, am I missing something?
We do not have API for Whisper/Barge currently. Please refer this article to understand how it works. https://success.ringcentral.com/articles/en_US/RC_Knowledge_Article/8086 . Please contact customer support for further support.
For monitoring calls, please check https://github.com/ringcentral/ringcentral-api-docs/blob/master/docs/notifications.md
Also, as the Whisper/Barge feature uses DTMF, you could use these features via RingCentral WebRTC. For further information please see this repository: https://github.com/ringcentral/ringcentral-web-phone