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

# Triggers

> Define how agent flows start — calls, messages, or API requests

A **Trigger Node** is the starting point of every Agent Flow. It determines *how* a workflow begins and *when* it should run. Every flow begins with exactly **one trigger**, and it must be the **first node** in the flow.

Triggers define not only the entry condition for your workflow (e.g., a call, a message, or an API request), but also the **published behavior** of your Agent—such as the required input, format, and runtime environment.

## Types of Triggers

<Frame>
  <img src="https://mintcdn.com/plivo/R0bB3pSVhMhsNJEx/aiagent/images/AgentTriggers.png?fit=max&auto=format&n=R0bB3pSVhMhsNJEx&q=85&s=3a8d79fef61af02eb4d8bcb5009c79e3" width="1158" height="1040" data-path="aiagent/images/AgentTriggers.png" />
</Frame>

| **Trigger Type**          | **Subtypes / Description**                                                                                                     |
| :------------------------ | :----------------------------------------------------------------------------------------------------------------------------- |
| **Incoming Conversation** | - When a Call is Received  - When a Chat Message is Received  - When an SMS is Received  - When a WhatsApp Message is Received |
| **API Request**           | Triggered externally via an authenticated HTTP call with optional input parameters                                             |

**Note:** The Start trigger placeholder is already present in every new flow. Click **“Select Trigger”** to open the drawer and choose a type.

## Configuring Trigger Types

### Incoming Call

* Choose **"When a Call is Received"** as your trigger.
* You’ll be able to configure a **Hangup Agent**—this is the fallback logic that runs if the user hangs up before the conversation completes.

### Incoming Chat Message

* Choose **"When a Chat Message is Received"**.
* You can configure **Quick Response Questions**—up to 5 preset, clickable suggestions to guide the user.

### Incoming SMS / WhatsApp Message

* These require **no additional configuration** after selection.
* Trigger activates when a new message is received on the selected channel.

Note: **Number Association:** Use the **Numbers** page in Settings to link your flow to a specific phone number.

### API Call Trigger

<Frame>
  <img src="https://mintcdn.com/plivo/R0bB3pSVhMhsNJEx/aiagent/images/APICallTrigger.png?fit=max&auto=format&n=R0bB3pSVhMhsNJEx&q=85&s=dfbe71e9cd4519f1d2c748aa42edc819" width="2764" height="1420" data-path="aiagent/images/APICallTrigger.png" />
</Frame>

* When selected, you’ll receive:
  * A **unique API endpoint URL**
  * **Authentication settings** (Basic Auth enabled by default)
  * A form to define **input variables**—key names and their expected data types, which can be used later in the flow.
* You can disable authentication (not recommended). We strongly advise **keeping the endpoint behind auth** for security.

## How to Switch a Trigger

You can change the starting point of your flow without rebuilding it:

1. Click the **options icon (⋮)** in the top-right corner of the trigger node.
2. Select **“Change Start Trigger.”**
3. Pick a new trigger type from the available options.
4. Configure your new trigger as needed.

**Note:** Switching triggers removes any configuration set on the previous trigger.