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Populate Retell Dynamic Variables with Google Sheets Data for Call Handling

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Agent Studio

Last update

Last update a month ago

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Overview

  • This workflow provides Retell agent builders with a simple way to populate dynamic variables using n8n.
  • The workflow fetches user information from a Google Sheet based on the phone number and sends it back to Retell.
  • It is based on Retell's Inbound Webhook Call.
  • Retell is a service that lets you create Voice Agents that handle voice calls simply, based on a prompt or using a conversational flow builder.

Who is it for

For builders of Retell's Voice Agents who want to make their agents more personalized.

Prerequisites

How it works

  • The webhook call is received from Retell. We filter the call using their whitelisted IP address.
  • It extracts data from the webhook call and uses it to retrieve the user from Google Sheets.
  • It formats the data in the response to match Retell's expected format.
  • Retell uses this data to replace dynamic variables in the prompts.

How to use it

See the description for screenshots!

  • Set the webhook name (keep it as POST).

  • Copy the Webhook URL (e.g., https://your-instance.app.n8n.cloud/webhook/retell-dynamic-variables) and paste it into Retell's interface. Navigate to "Phone Numbers", click on the phone number, and enable "Add an inbound webhook".
    Screenshot 20250331 at 16.38.06.png

  • In your prompt (e.g., "welcome message"), use the variable with this syntax: {{variable_name}} (see Retell's documentation).
    image.png

  • These variables will be dynamically replaced by the data in your Google Sheet.

Notes

  • In Google Sheets, the phone number must start with '+.
  • Phone numbers must be formatted like the example: with the +, extension, and no spaces.
  • You can use any database—just replace Google Sheets with your own, making sure to keep the phone number formatting consistent.

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