The NMI gateway screens transactions through several fraud layers — velocity rules, AVS and CVV filtering, the iSpyFraud rules engine, and tokenization via the Customer Vault. Together they let a merchant block, hold, or review suspicious transactions before they settle, without writing custom code. Each layer catches a different pattern, and they are most effective stacked.
Fraud screening sits inside the gateway itself, so it applies to e-commerce, keyed, and in-person transactions alike. Here is what each control does and how merchants tune them.
The fraud layers, one by one
Velocity rules
Limit attempts per card, IP, or amount over time — the main defence against card-testing.
AVS filtering
Compare the billing address entered against the issuer's record; reject or flag mismatches.
CVV filtering
Require the card-security code and reject transactions where it fails.
iSpyFraud
Custom rules engine — block, hold, or review by your own conditions.
Tokenization
Customer Vault stores cards as tokens, shrinking the data a breach could expose.
3-D Secure
Shift liability to the issuer on enrolled cards where the integration supports it.
People also ask about NMI fraud tools
What is iSpyFraud?
iSpyFraud is NMI's rules-based screening module. A merchant defines conditions — a dollar threshold, a mismatched billing country, an unusual card-attempt velocity — and iSpyFraud acts on matches by blocking, holding for review, or flagging the transaction. It is the most flexible of the gateway's fraud layers because the merchant writes the logic.
Does AVS/CVV filtering stop chargebacks?
It reduces some fraud and can help interchange qualification, but it is not a chargeback cure. AVS checks the billing address; CVV checks the card-security code. Both raise the bar for a fraudster but neither proves the cardholder authorised the purchase — which is what most chargebacks contest. Layer them with velocity limits and 3-D Secure for real protection.
What are velocity rules?
Velocity rules cap how many times a card number, IP address, or amount can be attempted within a time window. They are the front-line defence against card-testing attacks, where a fraudster runs thousands of small authorisations to find live card numbers. A sensible velocity limit stops the attack before it racks up authorisation fees and chargebacks.
Tuning the rules without blocking real customers
Every fraud control has a false-positive cost. Set velocity too tight and you decline legitimate repeat buyers; require strict AVS and you lose customers whose bank has an outdated address. The skill is calibrating to your real fraud exposure — start moderate, watch the decline and chargeback reports in Merchant Central, and tighten only where data justifies it.
On reseller-managed accounts, some fraud settings are configured by the payment company. If a control you need is locked, your reseller can adjust it.
FAQ
What fraud tools does NMI include?
Velocity rules, AVS and CVV filtering, iSpyFraud custom screening, tokenization, and 3-D Secure where supported.
What is iSpyFraud?
The gateway's rules engine — you set conditions that block, hold, or flag suspicious transactions.
Will these stop all chargebacks?
No. They reduce fraud and improve some qualification, but chargebacks have many causes. Layer the controls for best effect.
Can I set these myself?
Often yes, in gateway settings. On reseller-managed accounts the provider may control some of them.