Connect Retell Voice Agents to custom functions

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Important notice

This workflow is provided as-is. Please review and test before using in production.

1. Workflow Overview

This workflow allows you to trigger custom logic in n8n directly from Retell's Voice Agent using [Custom Functions](https://docs.retellai.com/build/conversation flow/custom function custom function...

Best for

Support Chatbot automation workflows
AI Chatbot automation workflows
intermediate n8n builders looking for reusable templates

Tools used

n8n-nodes-base.webhook, n8n-nodes-base.respondtowebhook, n8n-nodes-base.set, n8n-nodes-base.stickynote

Source and attribution

This workflow is cataloged by N8N Workflows and links back to its original n8n.io source page by Agent Studio.

Original n8n.io source

1.1 Workflow description

Title: Connect Retell Voice Agents to custom functions
Workflow name: Connect Retell Voice Agents to custom functions

Overview

This workflow allows you to trigger custom logic in n8n directly from Retell's Voice Agent using Custom Functions.
It captures a POST webhook from Retell every time a Voice Agent reaches a Custom Function node.
You can plug in any logic—call an external API, book a meeting, update a CRM, or even return a dynamic response back to the agent.

Who is it for

For builders using Retell who want to extend Voice Agent functionality with real-time custom workflows or AI-generated responses.

Prerequisites

Have a Retell AI Account
A Retell agent with a Custom Function node in its conversation flow (see template below)
Set your n8n webhook URL in the Custom Function configuration (see "How to use it" below)
(Optional) Familiarity with Retell's Custom Function docs
Start a conversation with the agent (text or voice)

Retell Agent Example

To get you started, we've prepared a Retell Agent ready to be imported, that includes the call to this template.

Import the agent to your Retell workspace (top-right button on your agent's page)
You will need to modify the function URL in order to call your own instance.
This template is a simple hotel agent that calls the custom function to confirm a booking, passing basic formatted data.

How it works

Retell sends a webhook to n8n whenever a Custom Function is triggered during a call (or test chat).
The webhook includes:
- Full call context (transcript, call ID, etc.)
- Parameters defined in the Retell function node
You can process this data and return a response string back to the Voice Agent in real-time.

How to use it

Copy the webhook URL (e.g. https://your-instance.app.n8n.cloud/webhook/hotel-retell-template)
Modify the Retell Custom Function webhook URL (see template description for screenshots)
- Edit the function
- Modify the URL
Modify the logic in the Set node or replace it with your own custom flow
Deploy and test: Retell will hit your n8n workflow during the conversation

Extension Ideas

Call a third-party API to fetch data (e.g. hotel availability, CRM records)
Use an LLM node to generate dynamic responses
Trigger a parallel automation (Slack message, calendar invite, etc.)

👉 Reach out to us if you're interested in analyzing your Retell Agent conversations.

1.2 Logical Blocks

This catalog entry is organized from the workflow JSON. The node-level section below shows the executable blocks available for review before importing the template.

2. Block-by-Block Analysis

Block 1 - Webhook

Type / Role: n8n-nodes-base.webhook - webhook
Config choices: Version 2

Block 2 - Respond to Webhook

Type / Role: n8n-nodes-base.respondToWebhook - respondToWebhook
Config choices: Version 1.1

Block 3 - [Replace me!] Set response

Type / Role: n8n-nodes-base.set - set
Config choices: Version 3.4

Block 4 - Sticky Note

Type / Role: n8n-nodes-base.stickyNote - stickyNote
Config choices: Version 1

Block 5 - Sticky Note2

Type / Role: n8n-nodes-base.stickyNote - stickyNote
Config choices: Version 1

Block 6 - Sticky Note3

Type / Role: n8n-nodes-base.stickyNote - stickyNote
Config choices: Version 1

Block 7 - Sticky Note1

Type / Role: n8n-nodes-base.stickyNote - stickyNote
Config choices: Version 1

3. Summary Table

Workflow	Connect Retell Voice Agents to custom functions
Complexity	intermediate
Nodes	7
Categories	Support Chatbot, AI Chatbot
Author	Agent Studio
Published	30 Apr 2025

4. Reproducing the Workflow from Scratch

1. Download the workflow JSON

Use the JSON export at /data/workflows/3805/3805.json as the source template for this automation.
2. Import the template into n8n

Open n8n, import the downloaded JSON, and review each node before activating the workflow.
3. Configure credentials and variables

Replace placeholder credentials, API keys, webhook URLs, account IDs, and environment-specific values with your own settings.
4. Test with sample data

Run the workflow manually or in a staging workspace, inspect node output, and confirm downstream systems receive the expected data.
5. Activate and monitor

Enable the workflow only after testing, then monitor executions, errors, and rate limits during the first production runs.

5. General Notes & Resources

Review imported nodes carefully before activation. This catalog entry is intended to help you inspect the workflow structure, understand required services, and find related templates faster.

Node names, credentials, schedules, webhook paths, and external service limits may need adjustment for your workspace.

Download workflow JSON Original n8n.io source Support Chatbot workflows AI Chatbot workflows

Frequently asked questions

What does Connect Retell Voice Agents to custom functions do?

What do I need before importing this workflow?

Review the workflow JSON, configure any required credentials in n8n, and test the automation in a safe workspace before using it in production.

Can I customize this workflow?

Yes. Use the block-by-block analysis and the downloadable JSON to inspect each node, then adjust credentials, prompts, schedules, filters, or destinations for your Support Chatbot, AI Chatbot use case.

Agent Studio

13 workflows

Nodes

n8n-nodes-base.webhook n8n-nodes-base.respondtowebhook n8n-nodes-base.set n8n-nodes-base.stickynote

Complexity

intermediate

Published 30 Apr 2025

Likes 0

View on n8n.io Download Workflow

Install path: /data/workflows/3805/3805.json

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Connect Retell Voice Agents to custom functions

Workflow preview

Important notice

1. Workflow Overview

Best for

Tools used

Source and attribution

1.1 Workflow description

Overview

Who is it for

Prerequisites

Retell Agent Example

How it works

How to use it

Extension Ideas

👉 Reach out to us if you're interested in analyzing your Retell Agent conversations.

1.2 Logical Blocks

2. Block-by-Block Analysis

Block 1 - Webhook

Block 2 - Respond to Webhook

Block 3 - [Replace me!] Set response

Block 4 - Sticky Note

Block 5 - Sticky Note2

Block 6 - Sticky Note3

Block 7 - Sticky Note1

3. Summary Table

4. Reproducing the Workflow from Scratch

1. Download the workflow JSON

2. Import the template into n8n

3. Configure credentials and variables

4. Test with sample data

5. Activate and monitor

5. General Notes & Resources

Frequently asked questions