> ## Documentation Index
> Fetch the complete documentation index at: https://docs.thinnest.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Transfer Call

> Transfer live calls to human agents, departments, or external numbers with warm or cold handoff.

# Transfer Call

The **Transfer Call** tool lets your voice agent hand off a live call to a human agent, a specific department, or an external phone number. You can use cold transfers (immediate switch) or warm transfers (agent briefs the human before connecting).

## Transfer Types

### Cold Transfer

The AI agent connects the caller to the destination immediately. The caller hears ringing and then the human picks up.

```
Caller: "I need to speak to a manager."
Agent: "Of course, I'll transfer you now. One moment please."
→ Call transfers to +14155551234
```

### Warm Transfer

The AI agent first calls the destination, briefs the human on the caller's issue, then connects all parties.

```
Caller: "I have a billing dispute."
Agent: "Let me connect you with our billing team. One moment."
→ Agent calls billing team, provides summary
→ Caller is connected to the billing agent
```

## Configuration

### Via the Dashboard

1. Open your agent and scroll to **Voice Settings**.
2. Enable **Transfer Call**.
3. Configure transfer destinations:

| Setting                 | Description                                                 |
| ----------------------- | ----------------------------------------------------------- |
| **Default destination** | Phone number for general transfers                          |
| **Department routing**  | Map keywords to specific numbers                            |
| **Transfer type**       | Cold or warm transfer                                       |
| **Hold message**        | What the caller hears while being transferred               |
| **Fallback**            | What happens if the transfer fails (voicemail, retry, etc.) |

### Via the API

```bash theme={null}
curl -X PATCH https://api.thinnest.ai/agents/agent_abc123 \
  -H "Authorization: Bearer $THINNESTAI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "voice_tools": {
      "transfer_call": {
        "enabled": true,
        "type": "cold",
        "default_destination": "+14155551234",
        "department_routing": {
          "billing": "+14155552222",
          "sales": "+14155553333",
          "support": "+14155554444"
        },
        "hold_message": "Please hold while I transfer you.",
        "fallback_action": "voicemail"
      }
    }
  }'
```

## System Prompt Guidance

Tell your agent when and how to transfer calls:

```
If the caller asks to speak to a human, sales, billing, or support team,
transfer the call to the appropriate department:
- Sales inquiries → transfer to sales
- Billing questions → transfer to billing
- Technical issues you cannot resolve → transfer to support
- "Speak to a manager" → transfer to the default number

Before transferring, briefly summarize the caller's issue so the human
agent has context.
```

## Department Routing

You can route transfers based on conversation context. Configure department-to-number mappings, and the AI agent will automatically route to the right destination based on the caller's needs.

```json theme={null}
{
  "department_routing": {
    "sales": "+14155551111",
    "billing": "+14155552222",
    "technical_support": "+14155553333",
    "manager": "+14155554444",
    "scheduling": "+14155555555"
  }
}
```

## Transfer Failures

If the destination doesn't answer, thinnestAI handles it gracefully:

| Fallback Action   | Behavior                                        |
| ----------------- | ----------------------------------------------- |
| `voicemail`       | Leave a voicemail at the destination            |
| `retry`           | Try the transfer again after a short delay      |
| `callback`        | Collect caller's number and schedule a callback |
| `return_to_agent` | Bring the caller back to the AI agent           |