Name: Flash call verification
Brand: Sinch

Streamline UX and reduce costs with no compromise on security

Improved UX

Delight customers with smooth, simple authentication that’s up to 70% faster than the SMS industry standard.

Higher conversions

Don’t lose customers at the first hurdle. Build verification solutions to match expectations - quick and easy!

Lower acquisition costs

A premium verification service for less! Flash Call Verification can save up to 25% on OTP costs compared to SMS.

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Sinch has created a service that has been very helpful to our company. It's easy to integrate, easy for our users, and provides great results.

Alan Mamedi

CEO & Founder, Truecaller

Ever since we integrated Sinch's Flash Call verification, we've seen a record increase in successful verifications across the globe.

Ari Roisman

Co-Founder and CEO

illustration of a human using a desktop computer

Flash Call Verification code snippet

curl -X POST \
     --user "APPLICATION_KEY:APPLICATION_SECRET" \
     -H "Content-Type: application/json"  --data " \
        { \
                "identity": { \
                       "type":"number", \
                       "endpoint":"+1555123123" \
               }, \
               "method":"flashcall" \
        }" \
  "https://verificationapi-v1.sinch.com/verification/v1/verifications"

One simple solution for all your verification needs

Easy integration

Get verified in no time with only a few lines of code thanks to our lightweight SDK or REST API for Android.

Top-notch security

With a pool of over 1,000,000 numbers to draw on, Flash Call is as secure as a 6-digit OTP code. Need even more security? Let us know!

Automatic OTP capture

A seamless CX from the very first touchpoint. Flash Call Verification captures the one-time password (OTP) with no user action required.

Optimized routes

Get the best conversion rates with powerful real-time feedback - our reporting API continuously optimizes for the best routes.

Seamless UX

Deliver a friction-free UX! Our Android SDK manages the complete on-device call verification process from start to finish.

Satisfy compliance

An ISO27001-certified solution, governed by EU GDPR and enabled through cryptographically secure code generation and storage.

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Got questions? We've got answers!

What is Flash Call Verification?

With Sinch Flash Call Verification, phone numbers can be verified with minimal user interaction. A dropped call is placed and the incoming call number acts as the OTP code, just like with SMS. The code is processed automatically on Android for a seamless UX.
How does Flash Call Verification work?

A call is made to the user's mobile phone and a request is then passed to the provider’s backend to authenticate that user. The verification can happen automatically without the user even noticing via the SDK, or they can enter their phone number manually in a text field to get verified.
How can two-factor authentication protect sensitive data?

An additional layer of security, or a second factor, can protect users from fraudulent attempts to access online accounts. Further proof of ID in addition to a password, such as an OTP texted to a mobile phone, makes it much harder to get access.
How to use two-factor authentication to confirm user ID?

2FA pairs something a user knows with something they have - for example, a password and a mobile phone. It’s that second layer of security that helps protect an account. If someone is unable to input a PIN code sent via SMS to the mobile phone linked to the account, access is denied.
Does it work on platforms other than Android?

Flash Call Verification works seamlessly on Android but needs the user to input the OTP on the web and iOS. Due to the poor UX on iOS, we only recommend Flash Call for Android and web applications.