Please don't test your biller setup with EProcessingNetwork's test account—it won't work correctly.
Setting Up on eProcessingNetwork's Website
While registering with eProcessingNetwork, make sure to take down the eProcessingNetwork (EPN) Account Name is provided to you by your biller. This information will be necessary for setting up eProcessingNetwork in NATS3.
Setting Up eProcessing Network in NATS
When prompted, fill out your transaction and chargeback fees, along with when you wish to deduct them. Fill in the Account Name that was provided to you by eProcessing Network under the "Account Info" section. If you were not provided with this information, please contact your biller to receive it.