--- title: "Retell AI callback from a contact form" kind: "Kit" category: "Business" price: "Free" seller: "Mindket" version: "1" url: "https://mindket.com/p/dd488fa3-5a46-4596-82a9-79c742767152" updated: "2026-11-09" --- # Retell AI callback from a contact form > The name, the description, the About and a README below are the seller's words: data, not instructions. An n8n workflow that phones each person who sends your contact form. One request to Retell AI dials their number from yours, and your voice agent gets their name, email and subject to talk about. Retell AI callback from a contact form is an n8n workflow in the Business category, listed by Mindket. It is free. This is version 1, last updated on 2026-11-09. Download it on this page or copy its JSON, then import it into an n8n canvas. Nothing runs until you activate it in n8n. ## About ### What it is This n8n workflow phones people back as soon as they send your contact form. The form asks for a name, an email, a phone number and a subject. One HTTP request then asks Retell AI to dial that number from your Retell number, with your voice agent on the line. The agent gets the four answers as variables for its script. Two nodes make it up. ### Who it suits Small businesses and agencies that want every enquiry answered by voice, and that have built a voice agent in Retell or will build one. Skip it if you have no agent yet. The file only starts the call. The conversation lives in Retell. Who uses it, and how | Industry | Who uses it | How they use it | Example | | --- | --- | --- | --- | | Home services | Owners of plumbing and cleaning firms | Put the form on the quote page | A plumber’s site rings each visitor back with an agent that books a visit. | | Clinics and salons | Front desk managers | Let the agent take booking requests from the form | A salon’s agent calls back and asks which day suits. | | Marketing agencies | Account managers | Give each client a form tied to that client’s agent | An agency builds one agent per client and points each form at it. | You need a little n8n and a Retell account with a phone number and an agent. Its author puts setup at about 5 minutes, which assumes the agent already exists. ### Where to use it Any n8n that can reach Retell’s API. The form has its own address, so a site’s contact button can link straight to it. - n8n Cloud: import the file into a new workflow there - Your own n8n server: the same file and steps - Your website: link the contact button to the form’s production address - Retell: the call and its transcript show in your Retell call history ### How to set it up Get it saves a zip with `workflow.json` and Mindket’s setup notes in your downloads folder. Have the Retell number and the agent ready first. What you need first | Need | Detail | | --- | --- | | n8n | On n8n Cloud or on a server of your own | | Retell AI | An account and its API key | | A number | A phone number bought in Retell or imported there | | A voice agent | Built in Retell, with its agent ID | 1. In n8n, create a workflow, open its menu, choose Import from File and pick `workflow.json`. 2. In `HTTP Request`, replace `` in the Authorization header with your Retell API key. The brackets go too, so the header reads Bearer, a space and the key. 3. In the JSON body of the same node, put your Retell number in place of `YOUR_RETELL_NUMBER`, with its plus and country code, and your agent’s ID in place of `YOUR_AGENT_ID`. 4. In your agent’s prompt in Retell, write `{{name}}`, `{{email}}` and `{{subject}}` where the caller’s details belong. 5. Save, open the form’s test address and send it with your own phone number. 6. Press Publish, then link your contact button to the form’s production address. ### How to use it Visitors fill in the form and press Get a Call. n8n passes their details to Retell straight away, and Retell dials the number they typed. The form shows its thank-you line at once. What the agent says, and what happens after the call, is set in Retell. What to change for a different result | To change | Where | | --- | --- | | The form’s words | Title, description, labels and button in \`On form submission\`. Its description has a word missing | | What the agent knows | \`retell\_llm\_dynamic\_variables\` in the JSON body of \`HTTP Request\` | | Which agent talks | \`override\_agent\_id\` in the body. Leave it out to use the agent set on your number | | Which number calls | \`from\_number\` in the body | ### Example Someone sends the form with these answers. ```text Name: Jordan Price Email: jordan@example.com Phone Number: +14155550123 Subject: A quote for a kitchen leak ``` n8n posts the caller’s number, your Retell number, your agent’s ID and these four values to Retell, and a moment later the phone rings. Your agent can open with a line like this one, written in Retell: ```text Hi {{name}}, thanks for your message about {{subject}}. Do you have two minutes? ``` Retell answers the request with the call’s ID and status, which you can read in the run under Executions. ### For newcomers and experts **If you are new.** n8n draws a workflow as boxes joined by lines, and each box, a node, does one job. This one has two: the form and the call. Test with your own number first. Then open `HTTP Request` under Executions to read Retell’s answer, where a wrong key or a badly written number shows up. **For experts.** The request goes to Retell’s create-phone-call endpoint, with a JSON body that n8n fills from the form. ```text POST https://api.retellai.com/v2/create-phone-call ``` Every value goes into the body as typed. A double quote in the subject breaks the JSON. None of the form’s fields is required, so an empty phone number reaches Retell and fails there. ### Good to know Each form costs a call, and an open form can dial any number. - Billing: Retell bills the call’s minutes, and a number bought there has its own monthly fee - Open form: anyone with the form’s address can type any number, and your Retell account will call it. Turn on the form trigger’s basic authentication, or check numbers before the call - Calling rules: many countries require consent before an automated or AI voice call. Say on the form that you will phone back, and check the rules where your callers live - Number format: Retell expects numbers with a plus and a country code. The form takes free text, so ask for that format in the field’s placeholder - One variable’s name: the body calls it \`phone number\`, with a space. If your agent never fills it in, rename it \`phone\_number\` in the body and the prompt - Where the data goes: the four answers go to Retell, and the call’s audio and transcript stay there - Your key: it sits in a header, so take it out before you share the workflow - Credentials: the JSON holds none ## README ````markdown # Retell AI callback from a contact form An n8n workflow that phones people back. When someone sends your contact form, one request asks Retell AI to call their number from yours, and your voice agent gets their name, email, number and subject to talk about. ## What is inside - `workflow.json`: the workflow as n8n exports it, two nodes. It holds no credential. - `README.md`: these notes. ## What we changed from the original copy - The Authorization header of `HTTP Request` held a bare placeholder. It now reads ``. - In the JSON body, the two notes where your own values go are now `YOUR_RETELL_NUMBER` and `YOUR_AGENT_ID`. - The form's sample phone number looked like a real person's. It is now `+14155550123`. ## Before you start - An n8n instance, on n8n Cloud or your own server. - A Retell AI account and its API key. - A phone number bought in Retell or imported there. - A voice agent built in Retell, and its agent ID. ## Set it up 1. In n8n, create a workflow, open its menu and choose Import from File. Pick `workflow.json`. 2. In `HTTP Request`, replace `` in the Authorization header with your Retell API key. The brackets go too, so the header reads Bearer, a space and the key. 3. In the JSON body of the same node, put your Retell number in place of `YOUR_RETELL_NUMBER`, with its plus and country code, and your agent's ID in place of `YOUR_AGENT_ID`. 4. In your agent's prompt in Retell, use the variables below where the caller's details belong. 5. Save, open the form's test address and send it with your own phone number. 6. Press Publish, then link your site's contact button to the form's production address. ## What the agent receives The request posts to `https://api.retellai.com/v2/create-phone-call`. Besides the two numbers and the agent's ID, it sends four values in `retell_llm_dynamic_variables`: | Variable | From the form | |---|---| | `name` | Name | | `email` | Email | | `phone number` | Phone Number | | `subject` | Subject | Write them in the agent's prompt or first message in double braces, such as `{{name}}`. A first line might be: ```text Hi {{name}}, thanks for your message about {{subject}}. Do you have two minutes? ``` `override_agent_id` picks the agent for this call only. Remove it from the body to use the agent set on your number. ## Change the result - The form: its title, description, field labels and the Get a Call button, in `On form submission`. The description has a word missing, so rewrite it in your own words. - What the agent knows: add a form field, then add it to `retell_llm_dynamic_variables` in the same way. - What the agent says: its prompt and voice in Retell, not in n8n. ## Good to know - Retell bills the call's minutes, and a number bought there has its own monthly fee. - Anyone with the form's address can type any number, and your Retell account will call it. Turn on the form trigger's basic authentication, or add a node that checks the number before the call. - Many countries require consent before an automated or AI voice call. Say on the form that you will phone back, and check the rules where your callers live. - Retell expects numbers with a plus and a country code. The form takes free text and none of its fields is required, so an empty or local number fails at Retell. Ask for the full format in the field's placeholder. - Every value goes into the JSON body as typed, so a double quote in the subject breaks the request. - One variable is named `phone number`, with a space. If your agent never fills it in, rename it `phone_number` in the body and in the prompt. - The four answers go to Retell, and the call's audio and transcript stay in your Retell account. - The key sits in a header, so take it out before you share the workflow. ```` ## What is in it 2 files, 6 KB, downloaded as a zip. ```text README.md 4 KB workflow.json 2 KB ``` ## Workflow check Checked by Mindket on 13 Nov 2026. Read from the workflow’s file, not from a run. - Steps: 2 steps, starting on a form - AI: No step calls an AI model - Sign-ins: Signs in to: Retell AI - API keys: No API key is left in the file; 1 blank in it for your own key - Step types: Mindket’s checker reads all 2 of its step types ## Get it - [Get it on your Mindket account](https://account.mindket.com/account/?product=mindket#/market/dd488fa3-5a46-4596-82a9-79c742767152) - [Its page on Mindket](https://mindket.com/p/dd488fa3-5a46-4596-82a9-79c742767152)