"Authentication offered but not used" is one of the possible results from a 3D Secure (3DS) transaction. It means that either:
- the card issuer or cardholder is not enrolled for 3DS
- the shopper has skipped the authentication (this is sometimes possible if, for example, it is a newly issued card - this is up to the issuer)
We explain the MPI responses that relate to each 3DS result (and the limitations of the 3DS authentication service) in our XML API Integration Guide.