Plain-language definition
Verification by a missed call whose caller ID contains the code.
Technical definition
A service places a call to the user's number and terminates it before answer; the app reads the incoming number as the OTP. On the network it appears as bursts of unanswered short calls from rotating numbers.
Why it matters
FlashCall displaces billable SMS OTPs and requires voice-channel detection.
Last reviewed 2026-09-12 by the Guardivia QoS Engineering Team. Product facts on this page describe current capabilities; items marked “where supported”, “optional”, “integration” or “consultancy” are confirmed per deployment.