What does a 'Call-Me' response require from the merchant?

A 'Call-Me' response typically indicates that additional verification is needed before a transaction can be finalized. In this context, it requires the merchant to contact the issuer directly, which allows them to confirm the legitimacy of the transaction. This step is crucial for preventing fraud and ensuring that the transaction is authorized by the appropriate parties. By contacting the issuer, the merchant is engaging in a validation process that helps safeguard both the merchant's and the customer's interests.

The other options do not align with the procedures associated with a 'Call-Me' response. Completing a sales report, canceling the transaction, or processing a refund do not fulfill the specific requirement to verify the transaction by reaching out to the issuer.