---
title: "What is out-of-band verification?"
description: "What out-of-band verification means for payments and vendor changes, examples, why it beats replying to an email, and its limits."
url: https://realpayee.com/answers/what-is-out-of-band-verification
canonical: https://realpayee.com/answers/what-is-out-of-band-verification
date_published: 2026-10-05
date_modified: 2026-10-05
author: RealPayee
---

# What is out-of-band verification?

> Out-of-band verification means confirming a request through a different channel, using contact details you already had, rather than replying through the channel the request came from. For payments, that means checking an emailed bank change by calling or messaging the vendor's known contact. It defeats attackers who control one channel, such as a hacked mailbox.

Its strength depends on the second channel being bound to the real person. A phone-bound approval or an ID plus live selfie check is stronger than a call a cloned voice could answer.

_Published 2026-10-05 · Updated 2026-10-05 · By RealPayee_

## Examples

- An emailed bank change is confirmed by calling the number in the vendor master file.
- An urgent wire request from the CFO is confirmed by an approval sent to the CFO's registered phone, or in Slack or Microsoft Teams.
- A new vendor contact is confirmed with a second, previously known person at the vendor.

## Limits

- If the contact details came from the request, it is not out-of-band.
- If both channels are compromised (for example, a hacked phone account), it can fail.
- If it is skipped under pressure, it does nothing, so enforce it with a hold.

See the [glossary entry](https://realpayee.com/glossary/out-of-band-verification) and the [wire fraud prevention guide](https://realpayee.com/wire-fraud-prevention).

## Frequently asked questions

### Is two-factor authentication out-of-band verification?

It uses the same idea for logins. For payments, out-of-band verification confirms the request itself with the real person, not just that someone can log in.

### Is replying to the email out-of-band?

No. Replying goes back to the same channel, which may be controlled by the attacker.

## Related

- [Out-of-band verification](https://realpayee.com/glossary/out-of-band-verification) - Out-of-band verification is confirming a request through a separate channel and contact details the requester did not provide - for example, calling a... (markdown: https://realpayee.com/glossary/out-of-band-verification.md)
- [Wire fraud prevention: how to stop bank wire fraud](https://realpayee.com/wire-fraud-prevention) - Controls that prevent business wire fraud: out-of-band verification, payment thresholds, dual approval and audit trails. (markdown: https://realpayee.com/wire-fraud-prevention.md)
- [How do I verify a vendor bank account change?](https://realpayee.com/answers/how-to-verify-a-vendor-bank-account-change) - A step-by-step way to verify a vendor bank account change before you pay: freeze the change, confirm out-of-band with a known contact, check the account, get a second approval and keep a record. (markdown: https://realpayee.com/answers/how-to-verify-a-vendor-bank-account-change.md)
- [Vendor verification: how to verify vendor bank details before you pay](https://realpayee.com/vendor-verification) - A practical guide to vendor verification for finance teams: how to confirm vendor bank-detail changes, run callbacks, and prevent vendor impersonation fraud. (markdown: https://realpayee.com/vendor-verification.md)

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