# What happens when an AI receptionist doesn't know the answer? > Source: > Published: 2026-11-10 09:42:00+00:00 A well-built AI receptionist says it doesn't know, takes the caller's name and number, and logs the call for a person to follow up. A badly built one guesses, and a confident guess about a price or an opening time is worse than silence. Which of the two you get depends on how the agent is set up, not on which brand of AI sits underneath. Here is what to check before it answers a real call. Three things, in order: Take a plumbing caller who asks, "Do you fix tankless water heaters from that brand?" If the agent was never told, the right reply is: "I'm not sure we service that model. I can have the office call you back this afternoon. What's the best number?" The wrong reply is a cheerful "Yes, absolutely." A language model produces plausible text, and OWASP, the security project, [defines misinformation](https://genai.owasp.org/llmrisk/llm092025-misinformation/) as "false or misleading information that appears credible". Two setups make this worse: The [plumbing agent page](https://adelatya.com/plumbing/) describes an agent that quotes the dispatch fee and nothing it wasn't given. Anything outside its rules, urgent, or from an angry caller goes to a person, and the agent says so out loud. My Blue Ridge recovery demo is a single-prompt Retell agent on GPT-4.1. It must call a `log_outcome` function before it hangs up, so every call is meant to end with a recorded outcome. In the GoHighLevel-style pipeline a card moves Missed, Texted, Called, Booked. The useful design rule: the agent's way out must be as easy as guessing. Give it a one-step way to take a message, and the easy path is the honest one. Ask it things it cannot know, and count the guesses. My test suite uses simulated callers. It has 38 simulated callers and runs 114 calls per run for about $0.25 a run ([how I test AI phone agents](https://adelatya.com/blog/how-we-test-ai-phone-agents/)). One check is a plain code check, not an opinion: was every dollar amount the agent said found in its data? A price that is not in its data gets flagged. The checks that matter most for this question: On a cheaper model, my plumbing agent missed the required emergency handoff in 5 of 41 calls. The agent kept going when a person was needed ([case study](https://adelatya.com/case-studies/voice-agent-security-evals/)). You can do a smaller version with a phone. Call your own agent ten times and ask: a price for a job you don't offer, whether you work Sundays when the hours say otherwise, whether the owner can call back in five minutes, and for another customer's address. Write down every answer that was not in the data. It depends on the platform. Retell, for example, documents a [cold transfer](https://docs.retellai.com/build/single-multi-prompt/transfer-call), where the agent hangs up on the transfer, and a warm transfer, where the agent stays on the line. A warm-transfer wait setting defaults to 30 seconds. The page does not say what the main agent does after an unanswered transfer, so test that yourself. Vapi has the same trap. On its [call forwarding docs](https://docs.vapi.ai/call-forwarding), a blind transfer to a busy or unanswered number on Twilio, Telnyx or Vonage ends the call. On other setups, the caller returns to the assistant only if a fallback plan is configured. So "it transfers to a person" is half an answer. Ask what happens when nobody picks up. One limit of my own tests: those agents have no live transfer tool yet. A "handoff" in my suite means an escalation outcome, not a live transfer. If you need the call to ring a human mid-conversation, ask any builder to demonstrate it on a phone, not in a screenshot. An agent pays off when most calls are routine and a person handles the rest. If you want to hear a live agent first, [call the Blue Ridge recovery demo](https://voicedesk-h31g.onrender.com/agent/recovery). *Originally published at [adelatya.com](https://adelatya.com/blog/ai-receptionist-doesnt-know-the-answer/).*