Audio Response Unit

An audio response unit is an authorization for a credit card transaction that occurs electronically using a touch-tone phone. Audio response units are usually used by vendors in situations where their automatic credit card transaction procedures fail.

A common situation when an audio response unit is going to be employed is when someone tries to pay at a brick and mortar establishment with a foreign credit card. In these situations, the credit card scanning machines often have trouble scanning the foreign credit card. It might be necessary to use the audio response unit to process the credit card transaction.

When a credit card is approved by an audio response unit, the vendor receives authorization and capture, just like with any other transaction. The only difference is that the process happens over the phone. It is all handled automatically as well, using inputs through the phone's keys, without the need for person to person interaction.

More Glossary Terms Explained here