Flash Call

What is Flash Call?

A flash call is a phone-number verification method in which the platform places a call that is dropped before being answered, and the last digits of the caller ID serve as the verification code.

Flash call verification dials the user’s number and hangs up almost immediately. The verification code is embedded in the final digits of the incoming caller ID; on Android, the app reads it automatically from the call log, so the user often taps nothing at all. That convenience comes with dependencies: the method requires call-log permissions that Google has been progressively restricting, and on iOS it cannot auto-verify — the user would have to read and type the number manually. Flash call should not be confused with voice OTP, where the call is answered and a text-to-speech voice reads the code aloud; the two have different permissions, platform behavior, and security properties. Example: an Android-first app uses flash calls for frictionless sign-up, but switches to voice OTP for withdrawal confirmations, where an answered, human-verified call is preferable.

See BSG's OTP SMS vs. Flash Calls: Multi-Factor Authentication Solutions Compared for a closer look at how this plays out in practice.

Related terms

• Caller ID
• Voice OTP
• OTP (One-Time PIN Code)

Related BSG products

• 2FA/OTP Platform
• Bulk SMS