> ## 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.

# Write an SMS Autoresponder

> Build a keyword-based SMS autoresponder for automated replies

## Overview

This guide shows how to write an autoresponder for SMS text messages. Autoresponders can streamline marketing campaigns and subscription signups and reduce the amount of work humans have to do.

You can create an autoresponder either by using our PHLO visual workflow builder or our APIs. Follow the instructions in one of the tabs below.

<Tabs>
  <Tab title="Using API">
    Here’s how to use Plivo APIs to set up an SMS autoresponder.

    <h2 id="api-{{'Outline' | slugify}}">How it works</h2>

    <Frame>
      <img src="https://mintcdn.com/plivo/sqGJ0ONkT5kTuesy/images/sms-autoresponder.png?fit=max&auto=format&n=sqGJ0ONkT5kTuesy&q=85&s=efe5ae0859d2a62184abc7a876bec19e" alt="Outbound-SMS Flow" width="1446" height="774" data-path="images/sms-autoresponder.png" />
    </Frame>

    <h2 id="api-{{'Prerequisites' | slugify}}">Prerequisites</h2>

    To get started, you need a Plivo account —  [sign up](https://cx.plivo.com/signup) with your work email address if you don’t have one already. To receive incoming messages, you must have a Plivo phone number that supports SMS; you can rent numbers from the [Numbers](https://cx.plivo.com/phone-numbers) page of the Plivo console or by using the [Numbers API](/docs/numbers/). If this is your first time using Plivo APIs, follow our instructions to set up a Ruby development environment.

    <h2 id="api-{{'Create a Rails controller to receive and respond to SMS messages' | slugify}}">Create a Rails controller to receive and respond to SMS messages</h2>

    Change to the project directory and run this command to create a Rails controller for inbound messages.

    ```shell theme={null}
    $ rails generate controller Plivo sms
    ```

    This command generates a controller named plivo\_controller in the app/controllers/ directory and a respective view in the app/views/plivo directory. We can delete the view as we don’t need it.

    ```shell theme={null}
    $ rm app/views/plivo/sms.html.erb
    ```

    <h2 id="api-{{'Create the autoresponder application using Rails server' | slugify}}">Create the autoresponder application using Rails server</h2>

    Edit app/controllers/plivo\_controller.rb and paste into it this code.

    ```rb theme={null}
    include Plivo
    include Plivo::Exceptions
    include Plivo::XML

    class PlivoController < ApplicationController
      skip_before_action :verify_authenticity_token
      def autoresponder
    		from_number = params[:From]
    		to_number = params[:To]
    		text = params[:Text]

    		if text.downcase == "interested"
    			body = "Thank you for showing interest. One of our agents will contact you."
    		else
    			body = "Reply 'Interested' to connect with our agents"
    		end
    		response = Response.new
    		params = {
    			src: to_number,
    			dst: from_number,
    		}
    		response.addMessage(body, params)
    		xml = PlivoXML.new(response)
    		render xml: xml.to_xml
    	end
    end
    ```

    <h3 id="api-{{'Add a route' | slugify}}">Add a route</h3>

    Edit config/routes.rb and change the line

    ```ruby theme={null}
    Rails.application.routes.draw do
      get 'plivo/sms' 
    end
    ```

    to

    ```ruby theme={null}
    Rails.application.routes.draw do
      post 'plivo/autoresponder/' => 'plivo#autoresponder'
    end
    ```

    Start the Rails server.

    ```shell theme={null}
    $ rails server
    ```

    You should see your basic server application in action at [http://localhost:3000/plivo/autoresponder/](http://localhost:3000/plivo/autoresponder/).

    Set up ngrok to expose your local server to the internet.

    <Note>
      <strong>Note:</strong>
      For ngrok testing, add this line to config/environments/development.rb.<br />
      `config.hosts << /[a-z0-9-]+\.ngrok\.io/`
    </Note>

    <h2 id="xml-create-a-plivo-application-for-autoresponder">Create a Plivo application for the autoresponder</h2>

    Associate the Rails controller you created with Plivo by creating a Plivo application. Visit SMS > [Applications](https://cx.plivo.com/xml-applications) in the Plivo console and click on **Add New Application**, or use Plivo’s [Application API](/docs/account/api/application/#create-an-application).

    <Frame>
      <img src="https://mintcdn.com/plivo/EvRfP72Bjs4tuRt5/images/create-app-autoresponder.png?fit=max&auto=format&n=EvRfP72Bjs4tuRt5&q=85&s=7f9aa51d5cbdd884072e6a53b53df53e" alt="Create Application" width="2874" height="1574" data-path="images/create-app-autoresponder.png" />
    </Frame>

    <h2 id="xml-assign-a-plivo-number-to-the-application">Assign a Plivo number to the application</h2>

    Navigate to the [Numbers](https://cx.plivo.com/phone-numbers) page and select the phone number you want to use for this application.

    From the Application Type drop-down, select `XML Application`.

    From the Plivo Application drop-down, select `Autoresponder` (the name we gave the application).

    Click **Update Number** to save.

    <Frame>
      <img src="https://mintcdn.com/plivo/NFI9_HRHTMInDf93/images/assign-app-autoresponder.png?fit=max&auto=format&n=NFI9_HRHTMInDf93&q=85&s=904f86e58fe21b0df89043205e9c74c6" alt="Assign Phone Number to Plivo Number" width="2870" height="1574" data-path="images/assign-app-autoresponder.png" />
    </Frame>

    <h2 id="Test">Test</h2>
    Send a text message to the Plivo number you specified using any phone.
  </Tab>
</Tabs>