How to Verify a User With Dexatel Verify API: A Foolproof Guide

Once your users tap “Sign Up,” the next few seconds can make or break their experience. A smooth, instant verification flow builds trust and keeps them engaged. A slow and complex process, on the other hand, can make them abandon your app before even completing the registration.

This is exactly where the Verify API can help. It lets you send and check one-time passwords (OTPs) through SMS, Viber, WhatsApp, Telegram, voice, or flash call, so users can get verified quickly without any friction. In other words, you don’t need to worry about messy backend setups or lost users. 

In this article, we’ll talk about how to verify a user with Verify API, including how to configure your backend, send verification requests, handle OTP validation, and implement error handling and retries.

But first, let’s take a look at what the Dexatel Verify API is. 

What Is the Dexatel Verify API?

Before online security became what it is today, verifying users often meant slow emails, extra steps, and long forms. As mobile use grew, these methods started to fall behind. 

The API models today, like Dexatel Verify API, are changing that by making verification fast and easy. Dexatel’s verification API confirms real users in just a few seconds.

The process is simple. The system sends a one-time password to the user’s phone and checks it once entered. This confirms that the number belongs to a real person and keeps access secure without adding friction. 

You can integrate the API into any app or website and choose how the code is sent—SMS, flash call, etc.

How the Verify API Works

Here’s how to verify a user with the Verify API in a sequence that happens every time a user signs up or takes an action that needs confirmation.

Step 1

Your application sends a verification request to the API. You provide the user’s phone number and choose the delivery channel. This tells the system to generate a one-time password and start the verification process.

Step 2

The verification API delivers the OTP through the selected method. You can use SMS verification or another channel, such as Viber, WhatsApp, or flash call.

Step 3

The user receives the code on their device and enters it into your application. This confirms they have access to that phone number.

Step 4

Your application sends the entered OTP back to the verification endpoint. The API compares it to the original code and checks whether it is still valid.

Step 5

The system returns a verification response. If the OTP is correct, the response confirms success, and the user is verified. If the OTP is wrong or expired, the response indicates failure, so your app can take the next step, such as prompting for a retry.

How to Verify a User With Verify API

1. Get API Credentials

Before making any requests, you need to set up your Dexatel account:

• Sign up for a Dexatel account if you haven’t already.

• Retrieve your API key from the dashboard. This key is required for authentication in every API request.

2. Set Up Your Environment

Secure your API calls and prepare your backend:

• Always use HTTPS to encrypt requests.

• Configure your backend to send requests to Dexatel’s verification endpoints.

• Make sure your server can handle JSON requests and responses.

3. Send Your First Verification Request

Start the verification process by sending an OTP to your user. Here’s a sample request:

Request Example (JSON):

POST /verify

Host: api.dexatel.com

Authorization: Bearer YOUR_API_KEY

Content-Type: application/json

{

  "phone_number": "+1234567890",

  "channel": "sms",

  "sender_id": "MyApp",

  "message_template": "Your OTP code is {{code}}"

}

Sample Response:

{

  "status": "success",

  "verification_id": "abc123",

  "message": "OTP sent successfully"

}

Parameters Explained:

• phone_number: The user’s phone number in international format.

• channel: SMS, WhatsApp, Viber, flash call, voice, or Telegram.

• sender_id: Name displayed as the sender (if supported).

• message_template: OTP message format with a placeholder for the code.

4. Validate the OTP

After the user receives the OTP, your application should validate it using the verification endpoint:

Validation Request Example:

POST /verify/confirm

Host: api.dexatel.com

Authorization: Bearer YOUR_API_KEY

Content-Type: application/json

{

  "verification_id": "abc123",

  "otp_code": "654321"

}

Possible Responses:

• 200: OTP verified successfully.

• 400: Invalid OTP or missing parameter.

• 429: Rate limit exceeded, retry after the specified interval.

5. Handle Errors and Retries

Network issues or user delays may cause failures. Implement robust handling:

• Timeouts: Retry requests if a response isn’t received within a few seconds.

• Duplicate requests: Your system should be able to safely handle repeated OTP submissions.

• Fallback logic: Switch channels if delivery fails.

• Logging: Record all API interactions for troubleshooting and analytics.

6. Test and Deploy

Before going live, thoroughly test your integration:

• Use sandbox or staging mode to simulate requests without sending real OTPs.

• Test with various phone numbers, channels, and edge cases to ensure reliability.

• Monitor responses and logs for errors or delivery delays.

Once testing is complete and you know that your verification flow is secure, fast, and user-friendly, you can go ahead and move your integration to production.

Best Practices for User Verification

Creating a smooth and secure user verification process depends on thoughtful implementation and attention to detail. These practices help balance security and user experience.

Short and Time-Limited OTPs

Use five or six-digit codes that expire quickly, such as within 30 seconds or two minutes. A user would receive a code and have a brief window to enter it. Short-lived codes reduce the chance of interception or misuse while allowing the user to verify their identity quickly.

Fallback Routes

Messages sometimes fail due to network issues or carrier restrictions. Setting up alternative methods allows users to complete verification even when the initial delivery method fails. 

For instance, if an SMS cannot reach a user in a rural area, a flash call can complete the verification instead.

Monitor Delivery Reports

Analyzing message delivery helps spot patterns and address issues before they affect users. Dexatel’s analytics dashboard displays failed deliveries, delays, or repeated network problems. 

If multiple messages fail in a specific region, developers can adjust delivery timing or try alternative channels to improve success rates.

Localize Messages

Adapting messages to a user’s language and tone allows for faster response and builds trust. A user in France, for example, might receive an OTP in French with polite phrasing, while a user in Japan would see a message in Japanese written in a formal style. Localized messages feel familiar and relevant.

Encrypt All Stored Data

Storing OTPs in plaintext creates security risks. Encrypting codes before saving them protects sensitive information from unauthorized access. When a user submits a code, the system can compare it with the encrypted version safely, allowing for verification without exposing the actual OTP.

Troubleshooting and Error Codes

Handling errors during user verification can be tricky, but understanding common issues and their causes helps developers respond quickly.

Invalid API Key or Missing Parameters

If an API request fails with an authentication error, check that the API key is correct and included in the request header. Also, confirm that all required parameters, such as phone_number and channel, are present in the JSON body. For example, sending a request without a phone number will return an error indicating a missing field, prompting the backend to log the issue and alert the developer.

Rate Limit Exceeded (HTTP 429)

A 429 response indicates too many requests in a short period. Introducing short delays between retry attempts can prevent repeated failures. For instance, if multiple OTP requests occur within a few seconds for the same user, spacing the requests by a few seconds allows the system to process them without hitting the limit. Logging these occurrences helps monitor spikes in request activity.

OTP Expired or Reused

Codes have a limited lifetime. If a user attempts to submit an OTP after it expires, the verification will fail. Similarly, submitting the same OTP more than once triggers an error. Handling this involves informing the user that the code has expired and automatically generating a new OTP if needed. 

Delivery Failed (User Network Issue)

Sometimes messages do not reach users due to network problems or carrier issues. Developers can check the delivery status through the analytics dashboard and attempt to send the OTP via an alternative channel, such as Flash Call or Voice. Logging failed deliveries also helps identify regions or carriers that frequently encounter issues.

Benefits of Using the Dexatel Verify API

Here are some of the main benefits of using Dexatel’s Verify API: 

Reliability

Dexatel Verify API is built to keep your verifications running smoothly, no matter what. Thanks to carrier redundancy and global coverage, messages are automatically routed through the most reliable network. If one mobile carrier faces delays or downtime, traffic is rerouted to another provider to keep OTPs flowing. This guarantees high success rates, even during peak periods or in regions with unstable networks.

Scalability

Handling spikes in user activity is simple with Dexatel Verify API’s scalable infrastructure. The system distributes requests intelligently, avoiding slowdowns even when traffic increases during product launches or global events.

• Handles any size: From a few hundred verifications per day for startups to millions for large enterprises.

• Smart traffic distribution: Requests are routed intelligently to prevent slowdowns, even during product launches or global events.

• Focus on growth: Developers and teams can spend less time managing infrastructure and more time improving the product.

• Seamless expansion: The system adapts naturally as your user base grows, supporting higher volumes without extra setup.

Cost-Efficiency

Dexatel uses a pay-per-use pricing model that allows full control over expenses. Charges apply only to successful verifications, which means you don’t spend money on messages that fail or never reach users. This makes it easier to plan budgets and track how much each verification campaign costs in practice.

Smaller companies benefit from starting with minimal financial commitment, while larger organizations appreciate transparent reporting and predictable billing. Spending can increase or decrease in line with customer activity, allowing verification costs to stay aligned with actual demand.

Security

The security of OTP data is a top priority in Dexatel’s system. All codes are encrypted while being transmitted and while stored in the database. This prevents unauthorized access or tampering at any point in the process. 

The platform also follows international privacy regulations such as GDPR, which adds another layer of protection for personal data.

The API uses fraud detection mechanisms that identify suspicious activity, like multiple failed verification attempts or requests from unusual sources. This helps the developers maintain a secure environment without building extra security tools from scratch. 

User Experience

Dexatel Verify API adapts to users’ preferences and local conditions, making sure OTPs reach them quickly and smoothly. A seamless verification process keeps users moving through sign-up and login flows without frustration. Key advantages include:

• Multiple delivery channels: A range of options based on user preference or network conditions.

• Faster verification: OTPs arrive promptly, reducing friction during onboarding or login.

• Regional customization: Messages can be localized for language and tone, creating a familiar, user-friendly experience.

• Reduced drop-offs: Reliable delivery and natural flows encourage users to complete verification without abandoning the process.

• Consistent trust: A smooth, intuitive experience builds confidence in your app and its security measures.

To Conclude

With Dexatel Verify API, verifying your users doesn’t have to be complicated. You can send OTPs through multiple channels, handle retries, and monitor delivery, all from a single, reliable system. The API adapts no matter your user volume or location.

Short, time-limited OTPs, fallback routes, localized messages, and encrypted storage all come together to make verification fast, safe, and convenient.

Start using Dexatel and keep users moving through your app without friction.