Voice OTP / ACS
Automated voice authentication fallback for regions and carriers where SMS verification is not reliable enough on its own.
ACS is an automated calling service that links a stored authentication code to an outbound call, plays prerecorded multilingual voice prompts, and confirms whether the customer answered the call.
At a glance
Why ACS matters
ACS is designed for destinations or carriers where SMS authentication is unavailable, restricted, or not reliable enough.
Recorded voice scenarios can be configured in multiple languages to support broader international verification flows.
ACS improves authentication success and reduces customer complaints when SMS receipt fails in some overseas markets.
ACS can be paired with international SMS OTP flows for foreign-member signup and other high-friction verification cases.
How ACS works
The customer phone number is tied to the verification code stored in the calling workflow.
SureM triggers an outbound automated call and plays the appropriate prerecorded voice prompt.
The client side can verify whether the customer answered the call as part of the authentication workflow.
Reliability note
Common use cases
- ›Login and account verification
- ›Password reset flows
- ›High-value identity confirmation
- ›Fallback for failed SMS OTP