Presence is the production wrapper rather than the conversational capability: scoped system access, policies that constrain what an agent may do, an approved-action set, and an escalation path to a human. The framing treats an agent as something that acts inside your systems and therefore needs the controls any actor would need, rather than as a better answer engine.
Voice and chat agents have existed for years and have failed reliably at the same point — the moment they need to change something rather than say something. What was missing was never the conversation; it was scoped access, an action set somebody had enumerated, and a defined handoff. Teams built those by hand, badly, and mostly discovered the gaps in production.