Handle user input with DTMF

A building block that shows how to handle a user input with DTMF. The user enters an option on the keypad and the selected option is acknowledged via a text-to-speech message.

Example

Replace the following variables in the example code:

Key Description
NEXMO_NUMBER Nexmo Number to call.

Prerequisites

Create an application

A Nexmo application contains the required configuration for your project. You can create an application using the Nexmo CLI  (see below) or via the dashboard  . To learn more about applications see our Nexmo concepts guide.

Install the CLI

$ npm install -g nexmo-cli

Create an application

Once you have the CLI installed you can use it to create a Nexmo application. Run the following command and make a note of the application ID that it returns. This is the value to use in NEXMO_APPLICATION_ID in the example below. It will also create private.key in the current directory which you will need in the Initialize your dependencies step

Nexmo needs to connect to your local machine to access your answer_url. We recommend using ngrok  to do this. Make sure to change demo.ngrok.io in the examples below to your own ngrok URL.

$ nexmo app:create "User Input DTMF Example"  http://demo.ngrok.io/webhooks/events --keyfile private.key
Install dependencies

$ npm install express body-parser
Initialize your dependencies

Create a file named app.js and add the following code:

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const app = require('express')()
const bodyParser = require('body-parser')

app.use(bodyParser.json())

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Write the code

Add the following to app.js:

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const onInboundCall = (request, response) => {
  const ncco = [
    {
      action: 'talk',
      text: 'Please enter a digit'
    },
    {
      action: 'input',
      eventUrl: [`${request.protocol}://${request.get('host')}/webhooks/dtmf`]
    }
  ]

  response.json(ncco)
}

const onInput = (request, response) => {
  const dtmf = request.body.dtmf

  const ncco = [{
    action: 'talk',
    text: `You pressed ${dtmf}`
  }]

  response.json(ncco)
}

app
  .get('/webhooks/answer', onInboundCall)
  .post('/webhooks/dtmf', onInput)

app.listen(3000)

View full source 

Run your code

Save this file to your machine and run it:

$ node app.js

Prerequisites

Create an application

A Nexmo application contains the required configuration for your project. You can create an application using the Nexmo CLI  (see below) or via the dashboard  . To learn more about applications see our Nexmo concepts guide.

Install the CLI

$ npm install -g nexmo-cli

Create an application

Once you have the CLI installed you can use it to create a Nexmo application. Run the following command and make a note of the application ID that it returns. This is the value to use in NEXMO_APPLICATION_ID in the example below. It will also create private.key in the current directory which you will need in the Initialize your dependencies step

Nexmo needs to connect to your local machine to access your answer_url. We recommend using ngrok  to do this. Make sure to change demo.ngrok.io in the examples below to your own ngrok URL.

$ nexmo app:create "User Input DTMF Example"  http://demo.ngrok.io/webhooks/events --keyfile private.key
Install dependencies

Add the following to build.gradle:

compile 'com.nexmo:client:latest.release'
compile 'com.sparkjava:spark-core:2.7.2'
Initialize your dependencies

Create a file named DtmfInput.java and add the following code:

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@JsonIgnoreProperties(ignoreUnknown = true)
public static class DtmfPayload {
    private String dtmf;

    @JsonProperty("dtmf")
    String getDtmf() {
        return this.dtmf;
    }

    public static DtmfPayload fromJson(String json) throws IOException {
        return new ObjectMapper().readValue(json, DtmfPayload.class);
    }
}

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Write the code

Add the following to DtmfInput.java:

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/*
 * Route to answer incoming calls.
 */
Route answerRoute = (req, res) -> {
    TalkNcco intro = new TalkNcco("Hello. Please press any key to continue.");

    InputNcco input = new InputNcco();
    input.setEventUrl(String.format("%s://%s/webhooks/dtmf", req.scheme(), req.host()));
    input.setMaxDigits(1);

    Ncco[] nccos = new Ncco[]{intro, input};

    res.type("application/json");

    // com.fasterxml.jackson.databind.ObjectMapper;
    return new ObjectMapper().writer().writeValueAsString(nccos);
};

/*
 * Route which returns NCCO saying which DTMF code was received.
 */
Route inputRoute = (req, res) -> {
    DtmfPayload dtmfPayload = DtmfPayload.fromJson(req.body());

    TalkNcco response = new TalkNcco(String.format("You pressed %s, Goodbye.", dtmfPayload.getDtmf()));
    Ncco[] nccos = new Ncco[]{response};

    res.type("application/json");

    // com.fasterxml.jackson.databind.ObjectMapper;
    return new ObjectMapper().writer().writeValueAsString(nccos);
};

Spark.port(3000);
Spark.get("/webhooks/answer", answerRoute);
Spark.post("/webhooks/dtmf", inputRoute);

View full source 

Run your code

We can use the application plugin for Gradle to simplify the running of our application. Update your build.gradle with the following:

apply plugin: 'application'
mainClassName = project.hasProperty('main') ? project.getProperty('main') : ''

Run the following gradle command to execute your application, replacing com.nexmo.quickstart.voice with the package containing DtmfInput:

gradle run -Pmain=com.nexmo.quickstart.voice.DtmfInput

Prerequisites

Create an application

A Nexmo application contains the required configuration for your project. You can create an application using the Nexmo CLI  (see below) or via the dashboard  . To learn more about applications see our Nexmo concepts guide.

Install the CLI

$ npm install -g nexmo-cli

Create an application

Once you have the CLI installed you can use it to create a Nexmo application. Run the following command and make a note of the application ID that it returns. This is the value to use in NEXMO_APPLICATION_ID in the example below. It will also create private.key in the current directory which you will need in the Initialize your dependencies step

Nexmo needs to connect to your local machine to access your answer_url. We recommend using ngrok  to do this. Make sure to change demo.ngrok.io in the examples below to your own ngrok URL.

$ nexmo app:create "User Input DTMF Example"  http://demo.ngrok.io/webhooks/events --keyfile private.key
Install dependencies

$ composer require slim/slim:^3.8

Write the code

Add the following to index.php:

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$app = new \Slim\App;

$app->get('/webhooks/answer', function (Request $request, Response $response) {
    $uri = $request->getUri();
    $ncco = [
        [
            'action' => 'talk',
            'text' => 'Please enter a digit'
        ],
        [
            'action' => 'input',
            'eventUrl' => [
                $uri->getScheme().'://'.$uri->getHost().':'.$uri->getPort().'/webhooks/dtmf'
            ]
        ]
    ];

    return $response->withJson($ncco);
});

$app->post('/webhooks/dtmf', function (Request $request, Response $response) {
    $params = $request->getParsedBody();

    $ncco = [
        [
            'action' => 'talk',
            'text' => 'You pressed '.$params['dtmf']
        ]
    ];

    return $response->withJson($ncco);
});

$app->run();

View full source 

Run your code

Save this file to your machine and run it:

$ php -t . -S localhost:3000

Prerequisites

Create an application

A Nexmo application contains the required configuration for your project. You can create an application using the Nexmo CLI  (see below) or via the dashboard  . To learn more about applications see our Nexmo concepts guide.

Install the CLI

$ npm install -g nexmo-cli

Create an application

Once you have the CLI installed you can use it to create a Nexmo application. Run the following command and make a note of the application ID that it returns. This is the value to use in NEXMO_APPLICATION_ID in the example below. It will also create private.key in the current directory which you will need in the Initialize your dependencies step

Nexmo needs to connect to your local machine to access your answer_url. We recommend using ngrok  to do this. Make sure to change demo.ngrok.io in the examples below to your own ngrok URL.

$ nexmo app:create "User Input DTMF Example"  http://demo.ngrok.io/webhooks/events --keyfile private.key
Install dependencies

$ pip install 'flask>=1.0'
Initialize your dependencies

Create a file named handle-user-input.py and add the following code:

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from flask import Flask, request, jsonify
from pprint import pprint

app = Flask(__name__)

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Write the code

Add the following to handle-user-input.py:

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@app.route("/webhooks/answer")
def answer_call():
    for param_key, param_value in request.args.items():
        print("{}: {}".format(param_key, param_value))
    input_webhook_url = request.url_root + "webhooks/dtmf"
    ncco =[
        {
            "action": "talk",
            "text": "Hello, please press any key to continue."
        },
        {
            "action": "input",
            "maxDigits": 1,
            "eventUrl": [input_webhook_url]
        }
    ]
    return jsonify(ncco)



@app.route("/webhooks/dtmf", methods=['POST'])
def inout_webhook():
    data = request.get_json()
    pprint(data)
    ncco =[
        {
            "action": "talk",
            "text": "You pressed {}, goodbye".format(data['dtmf'])
        }
    ]
    return jsonify(ncco)

View full source 

Run your code

Save this file to your machine and run it:

$ python3 handle-user-input.py

Prerequisites

Create an application

A Nexmo application contains the required configuration for your project. You can create an application using the Nexmo CLI  (see below) or via the dashboard  . To learn more about applications see our Nexmo concepts guide.

Install the CLI

$ npm install -g nexmo-cli

Create an application

Once you have the CLI installed you can use it to create a Nexmo application. Run the following command and make a note of the application ID that it returns. This is the value to use in NEXMO_APPLICATION_ID in the example below. It will also create private.key in the current directory which you will need in the Initialize your dependencies step

Nexmo needs to connect to your local machine to access your answer_url. We recommend using ngrok  to do this. Make sure to change demo.ngrok.io in the examples below to your own ngrok URL.

$ nexmo app:create "User Input DTMF Example"  http://demo.ngrok.io/webhooks/events --keyfile private.key
Install dependencies

$ gem install sinatra
Initialize your dependencies

Create a file named dtmf.rb and add the following code:

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require 'sinatra'
require 'sinatra/multi_route'
require 'json'

helpers do
  def parsed_body
    JSON.parse(request.body.read)
  end
end

before do
  content_type :json
end

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Write the code

Add the following to dtmf.rb:

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route :get, :post, '/webhooks/answer' do
  [
    {
      action: 'talk',
      text: 'Please enter a digit'
    },
    {
      action: 'input',
      eventUrl: ["#{request.base_url}/webhooks/dtmf"]
    }
  ].to_json
end

route :get, :post, '/webhooks/dtmf' do
  dtmf = params['dtmf'] || parsed_body['dtmf']

  [{
    action: 'talk',
    text: "You pressed #{dtmf}"
  }].to_json
end

set :port, 3000

View full source 

Run your code

Save this file to your machine and run it:

$ ruby dtmf.rb

Try it out

Call your Nexmo Number. When the call is answered you will hear a menu. Press 1 on the keypad followed by the # key. You will then hear a text-to-speech message acknowledging your selected option.