Your wire fraud policy is a callback to a known number, which works right up until the number itself is the thing being faked. There is a second check that costs nothing, needs no system, and cannot be looked up by anyone who was not there.
On First American's fraud podcast, a former FBI special agent who spent his career chasing cybercriminals is asked the plain question: what should an ordinary person actually do. His answer starts where everyone's does. “If you’re in the middle of a real estate transaction and somebody wants you to move faster or change a number or change something, pick up the phone and call somebody.”
Then he removes the embarrassment, which is the real reason people skip it. “You don’t look dumb asking somebody for a little help.” The words he gives you: “I just want to double check this, you know. This is a lot of money to me. I don’t want to wire it to the wrong place.”
And then the check that is his own, and that nobody teaches: “Hey, that first time we met, do you remember where we met? Can you tell me where we met?”
He applies the same logic to the callback number itself: “you get something from your bank and your bank wants you to do something and they give you a number to call, don’t call that number. Go on the back of your ATM card and call that number.”
“Hey, that first time we met, do you remember where we met? Can you tell me where we met?”
Every technical control in a transaction can be imitated. Display names, reply-to addresses, letterhead, a phone number in a signature block — all of it is text somebody else can type. Shared memory is the one credential that was never written down anywhere to be stolen.
Make it a habit rather than an alarm. If the only time you ask an odd personal question is the moment you already suspect something, you will not ask it, because by then it feels accusatory. Ask it on ordinary calls, early, so it is just how you talk — and so the one time it matters, nobody has to work up the nerve.