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Multi-factor Authentication: 2FA vs. MFA vs. AMFA

This article was updated on April 17, 2024

Because cyberattacks are now more sophisticated than ever, it's no longer sufficient to protect sensitive information with just a username and password. Instead, your business should look to implement multi-factor authentication (MFA) to provide additional layers of security for your users.

Read on to learn more about the differences between 2FA vs. MFA, as well as adaptive multi-factor authentication (AMFA).

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What is 2FA? 

Two-factor authentication (2FA) is a process which requires two steps in order to verify a user. Rather than relying on just a password, a 2FA solution asks for an additional piece of information in order to gain access to an account. This second factor can come from one of the following categories:

  • Something the user knows: This could be a personal identification number (PIN), a secondary password, an answer to a security question, or a specific keystroke pattern.

  • Something the user has: This could be a user’s smartphone, a credit card, an email, a physical token that generates a code (known as a hard token), or a virtual soft-ware based security token (known as a soft token).

  • Something the user is: This is a more complex form of 2FA and relies on a fingerprint or other biometric to identify the user.

Most forms of  2FA involve a one-time password (OTP). With solutions like the Vonage Verify API, an SMS message, WhatsApp message, phone call, or email delivers the OTP to a user’s device. The user then inputs that OTP to gain access to the online resource in question.

For businesses just getting started with authentication, a 2FA solution like Vonage Verify API can be a wise choice. Relative to other authentication solutions, 2FA is more cost efficient and easier to set up on the backend. Likewise, because end users are likely already comfortable receiving text messages, phone calls, or emails, it means that they’re more likely to comply with the authentication solution requirements. This is a relatively easy and quick way to add another layer of security to your business’s online touchpoints.

What is MFA? 

Multi-factor authentication (MFA) requires the user to provide two or more verification factors to gain access to an online resource. Additional authentication factors make account access more secure. Accordingly, 2FA is a form of MFA. When comparing 2FA vs. MFA, it’s important to note that all types of 2FA fall under the MFA umbrella. Conversely, though, not all MFA is 2FA.

What is AMFA?

Adaptive multi-factor authentication (AMFA) uses contextual information and business rules to determine which authentication factors to apply in a particular situation for a given user. As the name implies, the MFA solution "adapts" based on the circumstances of the user at the time of login. An Identity Service Provider system will select the right authentication factors depending on a user's risk profile and behavior as part of an ongoing process instead of applying risk evaluation and elevation only once.

While AMFA is a more sophisticated form of authentication than 2FA or MFA, it's also more costly and more complex for businesses to set up. AMFA can be a good option for businesses that have the budget to invest in a more complex authentication solution and for businesses looking to protect highly sensitive data.

Because AMFA uses a broad set of factors to automatically assess which authentication touchpoints are needed, it offers an intersection between a good user experience and more robust layers of protection to access online resources. But that convenience comes at a cost — AMFA is typically the most expensive authentication solution, and it still requires the use of MFA and 2FA resources to make up part of the system.

What are the pros and cons of 2FA, MFA, and AMFA?

Here's a closer look at the advantages and disadvantages of each authentication solution:





  • Simple and effective
  • User-friendly
  • Scalable
  • Limited to one authentication factor


  • Offers additional layers of security

  • Time consuming for users
  • Less user-friendly than 2FA



  • Good user experience
  • Adaptable
  • Customizable

  • Expensive and time consuming to implement
  • Cannot stand alone without 2FA or MFA

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What other forms of authentication are used to prevent fraud?

Beyond simply deciding whether to go with 2FA, MFA, or AMFA, some businesses may want to consider whether specific forms of authentication can help them prevent fraud. Here are some of the advantages and disadvantages associated with each one:





  • Convenient; uses a technologythat most people already know well
  • Many devices now offer to automatically fill in an OTP for the user if it arrives via SMS, making the authentication process even easier
  • May not be an ideal choice for businesses that require especially strict security
  • Delivery may be inconsistent or delayed in areas with patchy coverage — for example, some international locations


  • Intuitive and convenient
  • Can be delivered in multiple languages to support a global customer base
  • Supports better accessibility for some users with disabilities
  • May not be as effective when the user is in a noisy environment


  • Can serve as a convenient primary or secondary channel for authentication
  • Uses end-to-end encryption by default
  • Businesses must be validated to use WhatsApp, increasing trust for regular users
  • Works on both cellular data and Wi-Fi connections


  • Requires users to have the WhatsApp application installed on their device


Silent Authentication

  • Validates a user in the background based on the phone number associated with their mobile data connection
  • Minimizes the potential security risks associated with social engineering schemes that attempt to intercept OTPs
  • Can be used as a primary verification channel, with automatic failover to other channels, such as SMS, voice, WhatsApp, or email, when needed
  • Requires a mobile data connection to work

How can businesses get started with an authentication solution?

Whatever type of authentication solution your business chooses, taking the first step to implement additional layers of security beyond just usernames and passwords is a necessity. If you're looking for a quick start and a solution that can easily scale, consider an offering like Vonage Verify API. All-in-one 2FA solutions like Verify API can offer your business a verification system that can seamlessly deliver OTPs to users across channels and even perform seamless silent authentication if desired. It's a cost-effective and efficient way to add extra security to your business's online resources.

If implementing a Know Your Customer strategy is top of mind for your business, Vonage Number Insight API may be of interest. It identifies phone numbers around the world to make sure you have accurate and updated contact information, so you know the best way to reach your customers and can more easily spot fraud attempts, and can also protect your business from account takeovers and SIM swap scams. 

Vonage Fraud Defender takes fraud prevention a step further by providing real-time alerts and automatic blocking of suspicious traffic to reduce risk from bots and artificially inflated traffic (AIT). These flexible, easy-to-implement API solutions can help you give customers a better authentication experience while protecting your revenue and reputation.

Ready to better protect your business using 2FA? Explore Vonage two-factor authentication solutions now.


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