# What is Flash Call verification?

> Flash Call is a number-verification technique that places a missed call to the user's phone with a one-time short MSISDN as the caller-ID. The user's app reads the last 4-6 digits of the incoming caller-ID — that is the OTP — and the call is hung up before it rings. The user sees nothing; the verification completes silently. It is faster, cheaper, and harder to spoof than SMS OTP.

- Canonical URL: https://www.broadnet.me/answers/what-is-flash-call-verification
- Language: en
- Last reviewed: 2026-05-27
- Publisher: BroadNet (https://www.broadnet.me)

## How it works end-to-end

Your app calls our /verify/start with a phone number and method=flashcall. We dial the number from a single-use MSISDN whose last digits encode the OTP. The Android CALL_LOG permission lets your app read the incoming caller-ID; it strips the last 4-6 digits, hashes them, and POSTs to /verify/check. If the hash matches, the user is verified. End-to-end: 3-5 seconds. Cost: 30-60% of SMS OTP.

## Why operators love it

Flash Call doesn't touch the SMSC, doesn't consume a billable SMS event, and doesn't burn an A2P trunk. It is a single CAMEL/SIP call setup that gets cancelled before connect — most operators treat it as an unanswered call (free or near-free). For high-volume OTP services in markets where SMS A2P pricing is punishing (India, Indonesia, Brazil), Flash Call drops verification cost dramatically.

## Where it doesn't work

iOS apps cannot read incoming caller-ID programmatically. Flash Call is Android-only (and only via the user granting CALL_LOG, which Google has been increasingly restrictive about — Android 11+ requires the app to be the default Caller ID app or use SMS_RETRIEVER as a fallback). Always pair Flash Call with an SMS-OTP fallback. BroadNet's /products/myotp service auto-falls-back from Flash Call → SMS OTP → WhatsApp OTP → Voice OTP in a single API call.

## Regulatory state

GSMA published RCC.20 guidelines for Flash Call in 2022, treating it as a legitimate verification technique. Some operators (parts of India, the UAE) have started classifying it as A2P and applying A2P pricing; others (most of MENA, EU) still treat it as a voice event. Pricing varies accordingly. We track per-country classification and price accordingly.

## Related

- [All answers](https://www.broadnet.me/answers)
- [Glossary](https://www.broadnet.me/answers)
- [What is OTP?](https://www.broadnet.me/answers/what-is-otp)
- [What is GSMA Open Gateway?](https://www.broadnet.me/answers/gsma-open-gateway)
- [What is SMS pumping / artificial inflated traffic (AIT)?](https://www.broadnet.me/answers/what-is-sms-pumping)
- [MyOTP](https://www.broadnet.me/products/myotp)
- [OTP service](https://www.broadnet.me/products/otp)