Decrypting Passwordless Login : Build with Callchimp Pt. 3

Rupsa Sarkar@rupsa
Jun 20, 2024
5 minute read59 views
Decrypting Passwordless Login : Build with Callchimp Pt. 3

In the ever-evolving landscape of cybersecurity, the quest for secure and user-friendly authentication methods led to the development of Passwordless Login with Voice OTPs. Let's delve into the technical intricacies of this innovative project and explore its robust architecture.

The Need for Enhanced Security

Traditional login methods often rely solely on passwords, leaving accounts vulnerable to hacking and unauthorized access. Password fatigue is a common issue, with users struggling to create and remember complex passwords for multiple platforms. Moreover, visually impaired individuals face additional challenges when trying to read text-based OTPs.

Introducing Passwordless Login with Callchimp

This innovative project aims to revolutionize the login experience by implementing a secure two-factor authentication system using Callchimp's Voice OTP feature. By delivering OTPs through voice calls, the project enhances security while simplifying the login process for users.

How It Works

Powered by Django and Django Rest Framework, the project utilizes Callchimp's Python SDK to seamlessly integrate with the platform's API. During registration, users' phone numbers are stored as subscribers in Callchimp's system. When it's time to log in, users receive a voice call containing the OTP, which they enter to access their accounts securely.

Meet the Project Head

Meet Sayak Saha, a dynamic Systems Engineer at TCS Digital, whose journey in the realm of technology is marked by a passion for innovation and a commitment to excellence. With a diverse background that includes internships at prestigious institutions like IIT Bombay and collaborations with seven startups as a full-stack developer, Sayak brings a wealth of experience and expertise to every project he undertakes.

Beyond his professional endeavors, Sayak is a fervent advocate for community engagement and knowledge sharing. You'll often find him at various community events across India, where he eagerly exchanges ideas, mentors aspiring technologists, and contributes to the collective growth of the tech ecosystem.

Who Benefits from Passwordless Login with Voice OTPs?

  1. Users Struggling with Password Fatigue:
  • Individuals tired of managing numerous complex passwords across multiple platforms find relief with voice OTPs, eliminating the need for password memorization.
  1. Visually Impaired Users:

    • Those with visual impairments who face challenges in reading text messages can seamlessly authenticate their accounts by listening to the clearly announced voice OTPs.
  2. High-Security Accounts:

    • Banks, financial institutions, and services dealing with sensitive information elevate their security standards by implementing voice OTPs, adding an extra layer of protection during logins and transactions.
  3. Targets of Phishing Attacks:

    • Users frequently targeted by phishing scams or suspicious texts benefit from the enhanced security of voice OTPs, which are less susceptible to interception compared to traditional text-based OTPs.
  4. Users in Remote Locations:

    • Individuals residing in areas with unreliable data reception maintain access to their accounts even in remote locations, as voice calls remain accessible where data signals may be weak or unavailable.
  5. Businesses with Call Centers:

    • Companies with established call centers streamline their verification processes by integrating voice OTPs, providing a more seamless authentication experience during customer support interactions.

Key Benefits

  • Enhanced Security: Voice OTPs provide an additional layer of security beyond passwords, reducing the risk of unauthorized access and phishing attacks.

  • Accessibility: Visually impaired users can easily authenticate their accounts without relying on text-based OTPs, promoting inclusivity.

  • Simplified User Experience: By eliminating the need for complex passwords, the login process becomes more streamlined and user-friendly.

  • Reliability: With robust exception handling and fail-proof mechanisms, users can trust that they will receive the OTP reliably every time.

Behind the Scenes: Understand the Architecture

1. Technology Stack:

  • Backend Framework: Django, coupled with Django Rest Framework for seamless API integration.

  • Authentication Mechanism: Two-factor authentication using Voice OTPs.

  • API Integration: Leveraging Callchimp's Python SDK to interact with the Callchimp API.

2. System Components:

  • User Registration Endpoint: Allows users to register their phone numbers, which are stored as subscribers in Callchimp's system using the Callchimp API.

  • Voice OTP Generation Endpoint: Initiates a call to the registered user's phone number via the Callchimp API, delivering the OTP through a voice call.

  • Login Verification Endpoint: Validates the OTP entered by the user, ensuring secure access to the system.

3. Flow of Operations:

  1. User Registration:

    • Users provide their phone numbers during registration.

    • The backend sends a request to the Callchimp API to create a subscriber, associating the phone number with the user's account.

  2. Voice OTP Generation:

    • When a user attempts to log in, the backend triggers a request to the Callchimp API to initiate a voice call to the registered phone number.

    • Callchimp's API delivers the OTP through the voice call, ensuring secure transmission.

  3. Login Verification:

    • Upon receiving the voice call, the user listens to the OTP and enters it into the system.

    • The backend verifies the OTP entered by the user against the one generated and sent via the Callchimp API.

    • If the OTP matches, the user gains access to the system; otherwise, access is denied.

Challenges and Solutions

While integrating Callchimp's API presented some initial challenges, the user-friendly dashboard and comprehensive documentation helped overcome them. Ongoing improvements, such as adding SSML support, aim to further enhance the user experience and functionality of the project.

Future Directions

The project's potential extends beyond login security. Discussions with the Callchimp team have explored possibilities such as using the system as a traditional Captcha alternative and integrating bi-directional conversational bots for user registration.


Passwordless Login with Callchimp represents a significant step forward in authentication technology. By combining the security of voice OTPs with the ease of use of Django, this project sets a new standard for login security and accessibility. As we continue to innovate and refine the system, the possibilities for enhancing user security and experience are endless.

Resources and Documentation

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