LiveKit Outbound Caller Voice Agent

Build and run a voice agent that makes outbound PSTN calls using LiveKit. This example wires up VAD, STT, LLM, and TTS into a Voice Pipeline and includes a small CLI for local development, health checks, and model prewarming.

Features

• Voice Pipeline with Silero VAD, Deepgram STT, OpenAI LLM + TTS
• Outbound PSTN calls via LiveKit SIP Outbound Trunks
• Callable tools for call control and basic appointment flows
• Simple CLI: dev, healthcheck, download-files, prewarm

Prerequisites

• Python 3.10+
• LiveKit Cloud project and lk CLI installed
• Accounts/API keys for OpenAI and Deepgram

Setup

Run the following commands to clone, create a virtual environment, and install dependencies.

Linux/macOS

git clone https://github.com/tetratensor/LiveKit-Outbound-Caller-Voice-Agent.git
cd LiveKit-Outbound-Caller-Voice-Agent
python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt

Windows instructions (click to expand)

:: Windows (CMD/PowerShell)
git clone https://github.com/tetratensor/LiveKit-Outbound-Caller-Voice-Agent.git
cd LiveKit-Outbound-Caller-Voice-Agent
python -m venv venv
venv\Scripts\activate
pip install -r requirements.txt

Configure environment

Copy .env.example to .env.local and fill in the values:

• LIVEKIT_URL
• LIVEKIT_API_KEY
• LIVEKIT_API_SECRET
• OPENAI_API_KEY
• DEEPGRAM_API_KEY
• SIP_OUTBOUND_TRUNK_ID (from steps below)

You can also populate LiveKit variables via CLI:

lk app env

Optional: pre-download models

Downloads/caches VAD model to avoid a cold start on first run:

python3 agent.py download-files

Validate configuration

python3 agent.py healthcheck

Run the worker (development)

python3 agent.py dev

Now the worker is running and waiting for dispatches to make outbound calls.

Create a Twilio SIP Outbound Trunk

1. Create a Twilio account
2. Get a Twilio phone number
3. Create a SIP trunk
   • Twilio Console → Explore products → Elastic SIP Trunking → SIP Trunks → Get started → Create a SIP Trunk
4. Configure SIP Termination
   • Termination → enter a Termination SIP URI
   • Create Credentials List (friendly name, username, password)

Create a LiveKit SIP Outbound Trunk

1. Copy outbound-trunk-example.json to outbound-trunk.json and update with your SIP provider credentials. Do not commit this file.
   • name: Any friendly name
   • address: Your provider's Termination SIP URI
   • numbers: Your Twilio phone number to call from
   • auth_username: Username from your credentials list
   • auth_password: Password from your credentials list
2. Create the trunk with the CLI:

lk sip outbound create outbound-trunk.json

3. Copy the SIPTrunkID from the response into .env.local as SIP_OUTBOUND_TRUNK_ID.

Make a call

With the worker running in a terminal, open another terminal and dispatch an agent to dial a number:

lk dispatch create \
  --new-room \
  --agent-name outbound-caller \
  --metadata "+1234567890"

Helpful commands

lk project list

lk sip outbound list

lk sip dispatch list

Troubleshooting

• Ensure all required environment variables are present: run python3 agent.py healthcheck.
• First run may download models; use python3 agent.py download-files to prewarm.
• For more logs, run with --log-level DEBUG, e.g. python3 agent.py --log-level DEBUG dev.

CLI reference

python3 agent.py dev            # run the worker locally
python3 agent.py healthcheck    # validate required env vars
python3 agent.py download-files # pre-download/cache models (e.g., VAD)
python3 agent.py prewarm        # alias to download/cache models