Missed Call-Based Two-Factor Authentication
2 Factor Authentication via Missed Call

What is 2-Factor Authentication via Missed Call
An Authentication factor which uses Missed/Dropped Call initiated from user's registered phone. A dropped/Missed Call is a call which gets disconnected by a dedicated phone number before getting answered. You can authenticate users using dropped/Missed Call service.
Advantages of 2-Factor Authentication via Missed Call
- Password-less Authentication.
- Low operational cost.
- Cheaper than OTP SMS Authentication.
- Cheaper than OTP Voice Authentication.
- Simple and secure HTTPS API based integration with your applications.
Most Commonly Used
- Sign up Verification.
- Leads Generation.
- Transaction Authorization.
- Member Account Verification.
- Cash on Delivery (COD) shipments.
Requirements
You need to avail dedicated missed call number.
Integrate our 2-Factor Authentication API.
API Work Flow
Our API handles all the authentication infrastructure. We have written a detailed documentation on 2-Factor Authentication via Missed Call, which you can forward to your development team.
- Step 1: Hit our API with details such as callback and other parameters.
- Step 2: Upon Success response, flash the missed call number to be dialed to your user.
- Step 3: User dials the missed call number.
- Step 4: Operator sends us the call details.
- Step 5: We forward that detail to your callback URL.
- Step 6: Upon capturing the final response with Success, your user is authenticated.
- Step 7: Take your authenticated user for further transactions.
Note: Callback parameter is mandatory, the response will be forwarded to this URL whether customer dialed the missed call number or not.
Download PHP Class Reference: Missed Call 2FA – PHP Class Reference
Missed Call Pricing
Frequently Asked Questions (FAQs) about 2-Factor Authentication via Missed Call
2FA Authentication via Missed Call is authentication by a missed call to consume a defined number for a user for identification purposes. The incoming call detail serves as a call identity for the user. Therefore system verifies the correct phone number of the user and adds an extra measure by making sure no calls are made by the users.
The process consists of:
- Prompting the User: The system requests the user to call a specific number.
- Missed Call Detection: A user calls the number from which the call automatically disconnects after a ring, so no charges are implicated.
- Verification: The system collects the caller's number and validates it against the registered number for checking authentication.
- Cost-Free: Since users are not charged for missed calls, this is free for them.
- User-Friendly: No need for codes or apps; provides direct authentication.
- Secure: Authentication is tied to the user's physical device.
- Widely Accessible: Available for any phone that can make calls, even a feature phone.
Yes. It confirms possession of the registered phone number by the user. In addition, other security measures should also be implemented, such as SIM swap fraud monitoring for better security.
Yes, Missed Call 2FA can be implemented for International users. Just make sure that the missed call numbers are reachable by the specific countries where your users are located.
- Costs: Missed call 2FA is more cost effective as no SMS costs are incurred.
- Security: Both methods are considered secure, but SMS-based 2FA is susceptible to interception, while missed calls safeguard against this scenario.
- User-Friendliness: Missed Call 2FA eliminates the need to enter codes and therefore is a value addition.
If the user is not able to make a missed call due to network issues or limitations, it is better to have some other alternative methods available for authentication, such as, for example, SMS codes or authenticator apps in place to let the user have account access.
- A virtual number should be established: A virtual number capable of detecting incoming calls without being answered should be purchased.
- Integration into Your System: An API could be used to monitor incoming missed calls and match them with user sessions.
- Automatic Verification: The user's number is verified and access is given right away as soon as a missed call is detected.
Greatly streamline implementation by partnering with a missed call specialist service provider.
Certainly, Missed Call 2FA has a number of constraints like the following:
- Network Restrictions: Some networks may block missed calls to certain numbers.
- International Variability: Call behaviors tend to vary from country to country, thus influencing the consistency.
- SIM Swap Vulnerability: If a user's SIM is swapped, unauthorized access could occur.
So, these are the parameters for checking and then we can also keep some lineups on security as well and check them based on the user base.
- Reliable Infrastructure: This facility guarantees early and accurate detection of missed calls.
- Easy Integration: APIs allow you to integrate into your existing systems easily and out of the box.
- Global Reach: Accessibility of international numbers, leading to a wider user base.
- 24/7 Support: All-day and night assistance for any of your technical needs.
Missed calls make 2-Factor Authentication added in Security while being user-friendly.

Testimonials
Why do Great Businesses Trust SMS Gateway Center?