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Detect whether an outbound call was answered by a human or an answering machine before your AI agent starts speaking.

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Clone and run the full working example

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Getting started

git clone https://github.com/vobiz-ai/Livekit-Vobiz-Machine-Detection-Agent-example.git
cd Livekit-Vobiz-Machine-Detection-Agent-example
pip install -r requirements.txt
python agent.py dev

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Overview

When making outbound calls at scale, many calls land on voicemail. This example shows how to detect a machine answer versus a human answer, and react accordingly - leaving a pre-recorded message for voicemail, or starting a live conversation with a human.

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How it works

  1. The agent dials out via Vobiz SIP using LiveKit’s outbound calling.
  2. When the call connects, the agent listens for audio patterns.
  3. If short silence followed by a beep is detected → voicemail detected.
  4. If conversational speech is detected → human answered.
  5. The agent responds appropriately for each case.

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Detection logic

SignalClassificationAgent action
Greeting + pause + beepAnswering machineLeave pre-recorded message
”Hello?” or conversational speechHumanStart live conversation
Long silenceUnknownDefault to human behavior

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Environment variables

.env
LIVEKIT_URL=wss://your-project.livekit.cloud
LIVEKIT_API_KEY=APIxxxxxxxxxxxxx
LIVEKIT_API_SECRET=secretxxxxxxxxxx
VOBIZ_SIP_DOMAIN=your-domain.sip.vobiz.ai
VOBIZ_USERNAME=your-username
VOBIZ_PASSWORD=your-password
OPENAI_API_KEY=sk-...
VOICEMAIL_MESSAGE_URL=https://your-server.com/voicemail.mp3