Integrating Dialpad with a REST API Using Spring Boot: OTP Verification and Document Retrieval


In this tutorial, we will guide you through integrating Dialpad with a REST API using Spring Boot. We will focus on verifying user authentication based on their phone number using an OTP (One-Time Password), and then sending a document from an AWS S3 bucket. This step-by-step guide will help you set up the necessary environment, configure Dialpad webhooks, implement the Spring Boot application, and test the integration.

Step-by-Step Tutorial to Integrate a REST API with Dialpad Using Spring Boot

Step 1: Set Up Your Environment

  1. Create a Dialpad Account:

    • Sign up for a Dialpad account if you don’t have one.
    • Obtain API credentials from Dialpad (API key, secret).

  2. Set Up AWS S3:

    • Create an AWS account if you don’t have one.
    • Set up an S3 bucket and upload the document you want to send.

  3. Prepare Your Development Environment:

    • Set up a new Spring Boot project using Spring Initializr (
    • Add dependencies for Spring Web, AWS SDK, and any other required dependencies.

Step 2: Create a Spring Boot Project

  1. Initialize the Project:

    • Use Spring Initializr to generate a new Spring Boot project with the following dependencies:

      • Spring Web
      • AWS SDK

  2. Add AWS SDK Dependency:


Step 3: Configure Dialpad Webhooks

  1. Create a Webhook in Dialpad:

    • Log in to your Dialpad dashboard.
    • Navigate to the Developer section and create a new webhook.
    • Set the webhook to trigger on specific events (e.g., when a user presses a number on the dialpad).

  2. Set the Webhook URL:

    • Provide the URL where your Spring Boot application will listen for webhook events.
    • Ensure your application can handle incoming POST requests.

Step 4: Implement the Spring Boot Application

  1. Application Properties Configuration:

    • Add your AWS and Dialpad credentials to the file.


2. Create the Main Application Class:

public class DialpadIntegrationApplication {

    public static void main(String[] args) {, args);

3. Create the Webhook Controller:

public class WebhookController {

    private String dialpadApiKey;

    private AmazonS3 amazonS3;

    private final Map<String, String> otps = new HashMap<>();

    public ResponseEntity<String> handleWebhook(@RequestBody WebhookEvent event) {
        if ("dialpad_number_pressed".equals(event.getEvent())) {
            String userPhoneNumber = event.getData().getPhoneNumber();
            String otp = generateOTP();
            otps.put(userPhoneNumber, otp); // Store OTP

            // Send OTP via SMS using Dialpad API
            sendOTPSMS(userPhoneNumber, otp);

            return ResponseEntity.ok("OTP sent");
        return ResponseEntity.badRequest().body("Invalid event");

    private void sendOTPSMS(String phoneNumber, String otp) {
        // Implement API call to Dialpad to send SMS
        RestTemplate restTemplate = new RestTemplate();
        HttpHeaders headers = new HttpHeaders();
        headers.set("Authorization", "Bearer " + dialpadApiKey);

        Map<String, String> requestBody = new HashMap<>();
        requestBody.put("to", phoneNumber);
        requestBody.put("message", "Your OTP is " + otp);

        HttpEntity<Map<String, String>> request = new HttpEntity<>(requestBody, headers);
        restTemplate.postForEntity("", request, String.class);

    private String generateOTP() {
        return String.valueOf((int) (Math.random() * 900000) + 100000);

4. Create the Verify Controller:

public class VerifyController {

    private AmazonS3 amazonS3;

    private String bucketName;

    private final Map<String, String> otps = new HashMap<>();

    public ResponseEntity<String> verifyOTP(@RequestBody OTPRequest otpRequest) {
        String storedOtp = otps.get(otpRequest.getPhoneNumber());

        if (storedOtp != null && storedOtp.equals(otpRequest.getOtp())) {
            String document = getDocumentFromS3("document-key");

            return ResponseEntity.ok("OTP verified. Document: " + document);
        return ResponseEntity.status(HttpStatus.UNAUTHORIZED).body("Invalid OTP");

    private String getDocumentFromS3(String key) {
        S3Object s3Object = amazonS3.getObject(bucketName, key);
        try (S3ObjectInputStream inputStream = s3Object.getObjectContent()) {
            return IOUtils.toString(inputStream, StandardCharsets.UTF_8);
        } catch (IOException e) {
            throw new RuntimeException("Error reading document from S3", e);

class OTPRequest {
    private String phoneNumber;
    private String otp;

    // Getters and Setters

5. Webhook Event Class:

public class WebhookEvent {
    private String event;
    private EventData data;

    // Getters and Setters

    public static class EventData {
        private String phoneNumber;

        // Getters and Setters

Step 5: Test Your Integration

  1. Run Your Spring Boot Application:

    • Start your Spring Boot application and ensure it is running.

  2. Test Sending OTP:

    • Trigger the webhook by pressing a number on the dialpad and check if the OTP is sent to the user’s phone.

  3. Test Verifying OTP and Sending Document:

    • Send a POST request to the /verify endpoint with the phone number and OTP.
    • Verify that the OTP is correct and the document from S3 is returned.

By following these steps, you will have integrated Dialpad with a REST API using Spring Boot to authenticate users via OTP and send documents from an S3 bucket. This tutorial provides a straightforward framework which you can expand upon based on your specific requirements.

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