The free community edition of ICTPBX, a multi-tenant IP PBX built on ICTCore and FreeSWITCH with an Angular web interface.
It is aimed at service providers and at anyone who wants to run PBX services for more than one organisation from a single installation. Tenants are separated properly rather than bolted on, so each one gets its own extensions, DIDs, trunks and routing without seeing anyone else's.
The usual PBX building blocks are there: extensions and device provisioning, inbound...