Merchant ID - This is a required field for the gateway. Merchant ID is a unique id that identifies you with the gateway provider. NMI refers to this as a userid.
RegKey - This is the gateway password and is a required field. NMI refers to this as password.
NMI URL – Enter the URL of the gateway. NMI hosts many private label gateways, therefore you must enter the URL for the gateway.
For example:
https://secure.cardflexonline.com/api/transact.php
NMI Test Account
Userid: demo
Password: Password