NSW Police are warning the public to stay alert to scam phone calls that use technology to disguise their true origin, making it appear the call is coming from a genuine police or law enforcement number.

The practice is known as ID phone spoofing or web-based ID spoofing. Here is a simple explanation of how it works.

When you receive a phone call, your phone displays the number the caller says they are calling from.

Normally, that is the caller’s real number. But spoofing allows a scammer to tell the phone network to display a different number entirely, one they have chosen, such as the number for your local police station.

They do this using internet-based calling services that let the caller type in whatever number they want to appear on your screen.

The phone network simply passes that number on to your phone without checking whether it is real. Your phone has no way to know the difference.

This means that even if you look up the number and it matches a real police station, the call may still be coming from a scammer sitting anywhere in the world.

The image supplied by NSW Police shows what this looks like in practice. A call appears on screen to be coming from The Rocks Police Station on (02) 8220 6399.

In a real scam, the caller would then claim to be a police officer and use that fake number to convince you the call is genuine.

NSW Police are clear that police will never call you to request access to your computer or bank account, demand immediate payment, or threaten you with arrest or deportation. If you receive a call making any of these demands, hang up immediately.

Do not provide personal or financial information. Do not make any payments by transfer, gift card or cryptocurrency. Do not allow yourself to be pressured into acting quickly.

If you receive a threatening call, hang up and contact police directly on 131 444 using a number you have looked up yourself, not one provided by the caller.

Report scams at scamwatch.com.au. Anyone who believes they have been a victim of a data breach or identity theft should contact ID Support NSW and report to ReportCyber at cyber.gov.au/report-and-recover/report.