The Matrix protocol powers an open network for secure, decentralized communication.
From the Matrix.org home page:
Maintained by the non-profit Matrix.org Foundation, we aim to create an open platform which is as independent, vibrant and evolving as the Web itself… but for communication.
As of June 2019, Matrix is out of beta, and the protocol is fully suitable for production usage.
Matrix is great for real-time communications, including voice and video. It features end-to-end encryption (based on the algorithm popularized by Signal), and does a lot of bridging.
The bridging aspect might be something to look at for Moa, including using Matrix as the bridge into specific systems.