How to implement call greeting retries in voice agents

This guide demonstrates how to create a voice agent that repeats a greeting when there's no response, and gracefully ends the call after multiple attempts.

Implementation Steps

You can implement a call greeting retry mechanism using the away state, which is triggered when both the agent and user are silent for a specified timeout period. Here's how to set it up:

1. Create a counter to track greeting attempts

Initialize a counter variable to keep track of how many greeting attempts have been made.

2. Set up the initial greeting

Implement the initial greeting in the on_start method, which is called when the agent session begins.

3. Implement retry logic using the `away` state

Use the on_away callback to detect when both the agent and user have been silent for a period of time, and repeat the greeting if the maximum number of attempts hasn't been reached.

4. Add call termination after maximum retries

After reaching the maximum number of retry attempts, gracefully end the call with a final message.

Code Example

1import asyncio
2
3from livekit.agents import (
4    Agent,
5    AgentServer,
6    AgentSession,
7    JobContext,
8    UserStateChangedEvent,
9    cli,
10)
11from livekit.plugins import openai, deepgram, cartesia, silero
12
13server = AgentServer()
14
15@server.rtc_session(agent_name="my-agent")
16async def entrypoint(ctx: JobContext):
17    session = AgentSession(
18        vad=silero.VAD.load(),
19        llm=openai.LLM(model="gpt-4o-mini"),
20        stt=deepgram.STT(),
21        tts=cartesia.TTS(),
22        user_away_timeout=10.0,  # seconds before user is marked "away"
23    )
24
25    greeting_attempts = 0
26    max_attempts = 3
27    inactivity_task: asyncio.Task | None = None
28
29    async def handle_inactivity():
30        nonlocal greeting_attempts
31        greeting_attempts += 1
32        
33        if greeting_attempts < max_attempts:
34            await session.generate_reply(
35                instructions="The user hasn't responded. Repeat your greeting and ask if they're there."
36            )
37        else:
38            await session.generate_reply(
39                instructions="Say that you haven't received a response and will end the call now."
40            )
41            await asyncio.sleep(2)  # Let the message play
42            session.shutdown()
43
44    @session.on("user_state_changed")
45    def _user_state_changed(ev: UserStateChangedEvent):
46        nonlocal inactivity_task, greeting_attempts
47        if ev.new_state == "away":
48            inactivity_task = asyncio.create_task(handle_inactivity())
49            return
50
51        # User responded - cancel inactivity handling and reset counter
52        if inactivity_task is not None:
53            inactivity_task.cancel()
54            inactivity_task = None
55            greeting_attempts = 0
56
57    await session.start(
58        agent=Agent(instructions="You are a friendly assistant. Greet the user warmly."),
59        room=ctx.room
60    )
61
62    # Initial greeting
63    await session.generate_reply(
64        instructions="Greet the user and ask how you can help them today."
65    )
66
67if __name__ == "__main__":
68    cli.run_app(server)

How It Works

This implementation will:

Start the call with the greeting message – The initial greeting is generated using session.generate_reply() after the session starts
Track the number of attempts made – The greeting_attempts counter increments with each retry
Repeat the greeting when no response is detected – The user_state_changed event fires with new_state == "away" when the user has been silent for the configured timeout
End the call after 3 unsuccessful attempts – After reaching max_attempts, the call is terminated gracefully using session.shutdown()
Reset on user response – If the user speaks at any point, the retry counter resets to zero

Configuration

The away state is automatically triggered after a period of silence from both the agent and user. Configure the timeout duration using the user_away_timeout parameter when creating your AgentSession:

1session = AgentSession(
2    # ... other config ...
3    user_away_timeout=10.0,  # seconds before user is marked "away"
4)

Additional Resources

For more examples and advanced implementations, you can refer to our voice agents examples repository.

Read related documentation

LiveKit Agents overview - Get started with voice AI agents
Agent session lifecycle - Manage state across sessions
Voice pipeline overview - Configure your voice AI pipeline

Find more Agents guides

How to detect when an agent has finished speaking - Track playback completion events
Building multi-agent architectures - Best practices for multi-agent systems

How to implement call greeting retries in voice agents

Implementation Steps

1. Create a counter to track greeting attempts

2. Set up the initial greeting

3. Implement retry logic using the `away` state

4. Add call termination after maximum retries

Code Example

How It Works

Configuration

Additional Resources

Read related documentation

Find more Agents guides

Agents overview

Quickstart guide

Agent models

Building multi-agent architectures with LiveKit agents

Can you increase agent deployment limits?

Implementation Steps

1. Create a counter to track greeting attempts

2. Set up the initial greeting

3. Implement retry logic using the away state

4. Add call termination after maximum retries

Code Example

How It Works

Configuration

Additional Resources

Read related documentation

Find more Agents guides

Read related documentation

Agents overview

Quickstart guide

Agent models

Find more Agents guides

Building multi-agent architectures with LiveKit agents

Can you increase agent deployment limits?

3. Implement retry logic using the `away` state