What is P2A Based Authentication?

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Amit Gairola

mins read

July 8, 2024

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Key Takeaways

  1. P2A-based authentication enhances security by involving user-initiated interactions, reducing the risk of fraud and unauthorized access.
  2. The method offers a seamless and frictionless user experience, simplifying the authentication process into a single step and increasing conversion rates.
  3. P2A-based authentication supports global reach through the ubiquitous SMS channel, making it an effective tool for secure authentication across various industries.
  4. Unlike traditional OTP verification, P2A-based authentication minimizes the risk of interception and phishing attacks by leveraging user participation.
  5. Industries such as BFSI, e-commerce, and hyperscalers benefit from P2A-based authentication due to its high security, ease of integration, and cost-effectiveness.

P2A messaging (Person-to-Application) based authentication refers to the process wherein a mobile user initiates interaction by sending an SMS to an application.

Unlike A2P (Application-to-Person) messaging, which involves businesses sending messages to users, P2A messaging involves the end-user triggering the interaction by sending an MO SMS to registered numbers such as shortcodes or long codes.

The MO SMS can be sent either manually by the user or triggered automatically by apps running on their device.

With P2A-based authentication, businesses can elevate their systems to modern standards, ensuring seamless and secure verification over various channels like Free-To-End-User (FTEU) codes, shortcodes, toll-free numbers, and long codes.  

This article explores the advantages of incorporating P2A-based authentication into your processes, its workings, and its differences from traditional OTP verification.

Get in touch with our team to know how you can implement P2A based authentication system.

How Does P2A Based Authentication Work?

P2A-based authentication involves several steps that ensure a secure and seamless user experience. Here’s how it works:

  1. User Initiates Message: The process begins when a user sends an MO SMS to a specific number provided by the application, this process can either be manual or automatically triggered by the application itself.
  2. Message Reception: The mobile network receives the MO SMS and routes it to the application’s messaging platform.
  3. Processing by Application: The messaging platform processes the MO SMS and verifies the user’s identity based on the content of the message and the sender's phone number or MSISDN.
  4. Authentication Response: The application sends a response back to the user confirming the authentication status, either through a follow-up MT SMS or an in-app notification.

Factors involved in P2A Based Authentication

  1. User’s Mobile Device: The device from which the user sends the Mobile originated SMS.
  2. Short Code or Long Number: The designated number to which the user sends the SMS.
  3. Mobile Network: The carrier network that facilitates the transmission of the SMS.
  4. Messaging Platform: The intermediary system that processes the incoming SMS and communicates with the application.
  5. Application Backend: The application’s backend system that verifies the user’s identity and manages the authentication process.

Benefits of P2A Based Authentication

  1. Seamless Device Pairing: P2A-based authentication seamlessly pairs the user's device with their account, significantly reducing the risk of authentication fraud. By leveraging the user's mobile number, businesses can ensure that each authentication request is genuine and tied to the correct device.
  2. Secured Transactions: Security is non-negotiable, especially when sensitive data and transactions are involved. P2A-based authentication supports multi-grade encryptions, ensuring that all communication between the user and the application remains secure. This added layer of security is crucial for industries like banking and e-commerce.
  3. Hassle-Free Integration: One of the standout features of P2A-based authentication is its backend-driven nature. The integration with mobile apps is seamless, requiring zero user input. This makes the authentication process entirely transparent to the end-user, enhancing their overall experience.
  4. Frictionless Process: Gone are the days of clunky sign-up processes. P2A-based authentication offers a frictionless approach to pairing devices and customer accounts during sign-up. This smooth one click process encourages higher conversion rates and reduces drop-offs.
  5. Increased Conversion Rate: Traditional authentication methods often involve multiple steps, leading to user frustration and abandonment. P2A-based authentication simplifies this into a single-step process, resulting in a higher conversion rate and a more satisfied customer base.
  6. Fraud Prevention: By pairing the user’s device with their account, P2A-based authentication helps mitigate potential fraud like smishing. This direct link ensures that even if a user's credentials are compromised, unauthorized access attempts can be identified and blocked.
  7. Global Reach: P2A authentication leverages the omnipresence of the SMS channel, allowing businesses to connect with users globally. This wide reach makes it an effective tool for secure authentication.

P2A Authentication vs Traditional OTP Verification?

P2A authentication differs from OTP verification on a lot of aspects.


P2A Authentication

OTP Verification


The user initiates the authentication process by sending an MO SMS to the application.

The application sends an OTP to the user in the form of a MT SMS, who then enters it to complete the authentication.


More secure due to user participation and the reduced risk of OTP interception.

Prone to interception via phishing or SIM swapping attacks.

User Experience

Simpler and more intuitive as users are familiar with sending SMS.

Requires users to wait for an OTP and enter it, which can be cumbersome.


Can be more cost-effective as it leverages existing short-messaging-service infrastructure.

Involves costs associated with sending OTPs to users.

Applications of P2A-Based Authentication

BFSI Sector:

  • Use Case: Secure login and transaction verification. As of now, they mostly use OTP SMS for banking industry.
  • Benefit: Reduces the risk of fraud and unauthorized access to financial accounts.

Payment Interface Registration:

  • Use Case: Streamlines the process of registering payment methods securely.
  • Benefit: Ensures minimal hassle and high security for users.


  • Use Case: Secure and scalable user access management across vast, distributed environments.
  • Benefit: Ensures only authorized users can access critical cloud resources.

E-commerce Websites:

  • Use Case: Provides secure and seamless user logins.
  • Benefit: Enhances security and improves user experience by minimizing friction during the login process.


P2A messaging based authentication is a powerful method that leverages the reliability and ubiquity of SMS technology to provide a secure and user-friendly authentication process.  

By involving the user in the authentication initiation, it offers enhanced security over traditional OTP methods. Its simplicity, global reach, and cost-effectiveness make it an ideal solution for various industries, from finance to healthcare.  

As digital security needs evolve, P2A based authentication stands out as a robust and reliable method to protect user identities and ensure safe online interactions.

P2A Authentication with Message Central

Message Central is a pioneer in CPaaS technology and provides a complete authentication suite. Businesses wanting to explore P2A authentication can get in touch with the team.

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