System Messages

Every conversation with an agent has recurring moments the LLM doesn’t need to reason about — the greeting when a user first joins, the wrap-up before a call ends, the polite check-in when things go quiet. System messages let you script these moments explicitly so the agent handles them consistently. Each system message is a short list of lines. If more than one is provided, the agent picks one at session time so repeat visitors don’t hear the same phrase every call.

The four system messages

Message	When it fires	Configured via
Welcome message	When the user joins the session	`welcome_message`
Idle callout	When the user has been silent for a configured time	`idle_timeout`
Exit heads-up	Shortly before `max_call_duration` is reached	`exit_heads_up_message` (also `warning_exit_message`)
Exit message	When the call ends (either user leaves or duration is hit)	`exit_message`

Welcome message

Fires as soon as the agent joins the session and the user’s media is ready. This is the first thing your agent says.

"welcome_message": {
  "messages": [
    "Hi, how are you doing today?"
  ],
  "wait_time": 1
}

Field	Type	Description
`messages`	string[]	One or more greetings. One is chosen per session.
`wait_time`	number	Seconds to wait after the user joins before speaking (avoids talking over a still-loading page). Default `1`.

Best practices

Keep it short — one sentence at most. It’s the first impression.
Match the agent’s persona from the system prompt. A support agent’s greeting should sound different from a coach’s.
Provide 2–4 variants so the greeting doesn’t feel canned to returning users.

Idle callout

Fires when the user has been silent for timeout seconds. Useful to check whether the user is still there before ending the session.

"idle_timeout": {
  "timeout": 30,
  "filler_phrases": [
    "Hey it's been a while since we last spoke, are we still connected?"
  ]
}

Field	Type	Description
`timeout`	number	Seconds of silence before the callout fires. Default `30`.
`filler_phrases`	string[]	One or more callout lines. One is chosen when the timeout hits.

Best practices

Don’t set the timeout too low — 20–30 s is natural. Lower feels twitchy.
Provide friendly, warm phrases. This moment often feels awkward if scripted robotically.
Have 3–5 variants so a user idling twice in one call doesn’t hear the same line.

Exit heads-up

Fires a configurable number of seconds before the session hits max_call_duration. Gives the user a gentle warning that time is almost up.

"exit_heads_up_message": {
  "callout_before": 10,
  "messages": [
    "We are almost at the end of our call, thank you for your time."
  ]
}

Field	Type	Description
`callout_before`	number	Seconds before session end at which the heads-up fires. Default `10`.
`messages`	string[]	One or more heads-up lines.

Exit message

Fires when the session ends — either the user leaves or max_call_duration is hit.

"exit_message": {
  "messages": [
    "We are at the end of our call, thank you for your time."
  ],
  "max_call_duration": 300
}

Field	Type	Description
`messages`	string[]	One or more closing lines.
`max_call_duration`	number	Seconds the session can run before this message fires and the call ends. Default `300`.

The equivalent field warning_exit_message also exists in the API for backward compatibility — use exit_heads_up_message for new agents.

Toggling messages on and off

Each of the four messages can be independently enabled or disabled via config.systemConfig:

"config": {
  "systemConfig": {
    "entryMessageToggle2": true,
    "idleCalloutToggle2": true,
    "exitHeadsUpToggle2": true,
    "exitMessageToggle2": true
  }
}

Set any toggle to false to keep the message configured but suppress it at runtime.

Full example

Configuring all four messages in a single avatars[] block:

"avatars": [
  {
    "avatar_key_id": "665a1170",
    "welcome_message": {
      "messages": [
        "Hi, I'm Priya. What brought you here today?",
        "Hey there — good to see you. What can I help with?"
      ],
      "wait_time": 1
    },
    "idle_timeout": {
      "timeout": 30,
      "filler_phrases": [
        "Still with me?",
        "Take your time — I'm here whenever you're ready."
      ]
    },
    "exit_heads_up_message": {
      "callout_before": 15,
      "messages": [
        "Heads up — we've got about fifteen seconds left before this call wraps."
      ]
    },
    "exit_message": {
      "messages": [
        "Thanks for chatting today. Take care!",
        "That's our time — great talking with you. Bye for now."
      ],
      "max_call_duration": 300
    }
  }
]

Introduction

Models

AI Teammates (Avatars)

Text to Video

The four system messages

Welcome message

Idle callout

Exit heads-up

Exit message

Toggling messages on and off

Full example

Next steps

Prompting

Templates

​The four system messages

​Welcome message

​Idle callout

​Exit heads-up

​Exit message

​Toggling messages on and off

​Full example

​Next steps

Prompting

Templates

The four system messages

Welcome message

Idle callout

Exit heads-up

Exit message

Toggling messages on and off

Full example

Next steps