FlashCall Authentication & Verification

What is FlashCall authentication?

FlashCall authentication, also called missed-call verification, confirms that a user controls a phone number by placing a very short call to it and hanging up before it is answered. The last digits of the calling number are the one-time code. On Android, an app with permission reads the incoming caller ID and completes verification automatically; elsewhere the user can enter the digits by hand. It is an alternative or fallback to SMS OTP.

How FlashCall works

The user enters a phone number in your app at sign-up or login.
Your platform requests verification from Wise Network for that number.
We place a short call from a calling number whose final digits are the code, and release it before it is answered.
The app reads the code. On Android, with the user's permission, the app reads the incoming number automatically. Otherwise the user types the last digits.
The code is checked and the number is verified.

FlashCall vs SMS OTP

	FlashCall	SMS OTP
How the code arrives	In the caller ID of a missed call	In the text of an SMS
Automatic on Android	Yes, with call log permission	Yes, with SMS retriever or similar APIs
iOS	User types the digits	Code suggested from the message
Cost	Usually lower, where operators allow it	A2P SMS termination rate
Operator stance	Some block or require a billed trunk	Standard A2P traffic

The full comparison, including fraud exposure, is in FlashCall vs SMS OTP.

Delivery on sanctioned routes

We deliver FlashCall only where it is permitted: on routes and trunks the destination operator accepts for this traffic. That keeps verification reliable, because flash calls on unapproved routes are increasingly detected and blocked, and it keeps us consistent with the detection products we build for operators.

Integration

FlashCall can run alongside SMS OTP on the same commercial relationship, so your flow can try one method and fall back to the other by country or device. Integration details are agreed during onboarding; see also OTP messaging.

For mobile operators

If you operate a mobile network and want to detect, block or bill flash calls arriving on your voice trunks, see FlashCall detection and monetization.

Frequently asked questions

How does FlashCall work step by step?

The app asks for the user's number, then requests verification from a FlashCall provider. The provider places a call to that number from a calling number whose last digits are the code, and releases it before it is answered. The app reads the incoming number, or the user types the last digits, and the code is checked.

Does FlashCall work on iPhones?

iOS does not let apps read incoming call logs, so on iPhones the user has to type the digits shown in the missed call. Many verification flows use FlashCall on Android and SMS OTP elsewhere.

Is FlashCall allowed everywhere?

Not everywhere on the same terms. Some mobile operators block flash calls or require them on a dedicated, billed trunk. We deliver FlashCall only on routes where it is sanctioned and tell you which destinations support it.

Why would a mobile operator block my flash calls?

Because verification moved from SMS to unbilled calls costs operators A2P revenue. Operators increasingly detect flash calls and either bill them on a dedicated trunk or redirect verification back to SMS. See FlashCall detection and monetization.