A service provided by acquirers to merchants that allows them to call a voice authorization center and obtain authorization for manual transactions exceeding the store's limit. It is also used as an alternative means of authorisation if the terminal cannot connect to the acquirer online. In this case, the merchant will call the voice authorization center and provide the relevant card and transaction information over the phone. The voice authorization center then sends the online authorization request to the issuer and provides the merchant with the authorization code from the card issuer. The merchant records this code on the sales receipt.