Aria
A voice agent that answers the phone for a home services business. It holds context through a call, works out urgency, checks real availability, books the slot, and sends an SMS confirmation. Retell AI for the voice layer, Claude and GPT for reasoning, Twilio for telephony.
Not the model. The guardrails. It cannot book a slot it has not verified, and it cannot quote a price it was not given. When it is unsure it escalates to a human with a summary, because an agent that confidently invents an appointment is worse than no agent at all.