The sophisticated fraud sees scammers purporting to be a bank worker, or from the police, attempting to dupe a person over the phone into revealing their PIN and handing their credit or debit card over to a courier or taxi, who may not know they are being used as part of the scam.The victim may be asked to ring the number on the back of their card, thereby further convincing the victim that the call is genuine, however the scammer keeps the line open so that the victim unknowingly talks to another member of the gang, posing as a bank employee.A number of reports of courier fraud have been made to police in Northern Ireland.Those most at risk are older people and vulnerable individuals but the PSNI is warning that everyone is potentially a victim.Scammers are always looking for new ways of defrauding the elderly and vulnerable, and the crime continues to evolve. It is vital that people stay vigilant. Courier fraudsters put a huge amount of time and effort into being convincing because the pay-off is immense.Detective Constable Stephen CrooksDetective Constable Stephen Crooks, from Organised Crime Branch, said: "The police or bank will never ask you for your PIN or credit card. They will never ask you to withdraw amounts of cash from your bank or bureau de change."If you are contacted by someone who asks for these, hang up. Then use a different line to report the call to police on 101 or allow at least five minutes for the line to automatically clear."A common scam is when suspects typically purport to be a police officer and request that you assist in an investigation into corrupt bank staff or counterfeit money being passed. They may also tell you that you may be entitled to a reward. Law enforcement agencies would never ask you to do this or offer a reward under these circumstances."We want people to question even truly genuine sounding calls and, most importantly, remember police and banks will never ask for your PIN or bank card, so you should never give these away."Ofcom's Director in Northern Ireland, Jonathan Rose, added: "Ofcom is working closely with the police and the telecoms industry to help stamp out courier fraud."Over the last year, a number of telephone providers have made changes to their networks to cut the time a phone line remains open to a couple of seconds. This action has stopped fraudsters from being able to stay on the line to impersonate a victim's bank or the police - a key feature of how this scam works. We have also been working to drive awareness among consumers to help them avoid falling victim to courier fraud."It's very encouraging to see this work paying dividends, with more fraudsters being foiled in their attempts to scam people. But we're fully aware that there's more work to do to prevent courier fraud completely. We are continuing our work in this area to ensure that the necessary technical changes are fully implemented across the telecoms sector as quickly as possible."