Guidance on authentication verification in 3DS in credit and debit transactions:
To confirm if authentication was applied during authorization, check the ECI value in Payment.Eci;
The API replicates the ECI provided by the merchant in Payment.ExternalAuthentication, but the actual value used by the card brand is the one in Payment.Eci.
If the provided MerchantId does not exist in the environment database (Production or Sandbox), the error "298 – Split payment facilitator data not found" will be returned.