iPayment "Credit Card Authorization" call failing

 We use iPayment for CC authorization and funds capture from Order Management/Quoting. It works fine in PROD, and I know that we have used in TEST env as well before. But recently, this iPayment call is failing consistently from all Order channels ( Order Mgmt Forms or API). 

iPayment setup seems to be fine in TEST env. When checked from iPayment Administrator responsibility, was even able to place a test trx from there, I do see entries in iPayment IBY tables. But from Forms or API, the call fails with error "Credit Card Auth Failure". In this case, I don't see an entry in iPayment tables in this scenario. Apache bounce doesnt seem to help. I know for a fact I am using the correct test CC, so its not data issue.