VANCOUVER -- It starts with a call claiming to come from your bank’s fraud department informing you that there have been suspicious charges on your credit card, or possibly that someone has applied for credit in your name. They don’t ask you for any information but instead ask you to contact the fraud department by calling the number on the back of your credit or bank card.

Audrey Cerny of Metro Vancouver received such a call. In a panic, she hung up, got her credit card out and called the number on the back of credit card. She says she was put through to someone in the fraud department.

“He proceeded to ask a whole bunch of questions to confirm who I was. Email address, credit card number, birth date, full name,” Cerny said.

She even verified the security code on the back of her credit card.

However, Cerny wasn’t talking with her bank at all. The scammers hadn’t hung up and were still on the line.

Here is how it works. Even though you hang up, on landline phones the caller can remain on the line. It could be seconds, though in Cerny’s case, she says it was longer than that.

Typically, the scammers will work in teams. When you pick up the phone again, they will play a recorded dial tone, then "answer the call" after you dial – and even pretend to transfer you to someone else.

In less than 24 hours, Cerny says the culprits rang up $23,000 in charges on her credit card. Fortunately, she checked her account the next day morning and noticed a "test" charge of $5 made in Ontario. She reported the fraud to her bank before the other pending charges posted to her account.

“It’s still an ongoing issue that we see here today at the anti-fraud centre,” said Jeff Thomson with the Canadian Anti-Fraud Centre.

The delayed disconnect feature was meant for convenience. Years ago, when many of us still landlines, we could answer the phone in one room and then hang up and pick up a phone extension in another private area of the house to continue the conversation.

“In today’s world, you got to wonder if the delayed disconnect feature is even needed,” said Thomson.

Ron Kubara of Surrey wonders the same thing. He recently received one of those scam calls but when he hung up and picked up the phone again to call his bank, he got suspicious.

“The dial tone did not sound correct,” he said.

He ended up using his cellphone and while he was on the phone, his landline rang again. It was the scammer calling again to give him the transaction number on the "fraudulent" credit card charge; an attempt to get him to hang up and call his bank immediately before the call disconnected from the fraudster.

What are the telecoms doing to prevent it?

Both Cerny and Kubara have Shaw as their provider. In an email, Shaw told CTV News that it is “working with our teams to internally shorten our call clearing delay time to help reduce the risk posed by this type of fraudulent activity.”

Telus confirmed its line could stay active for up to 10 seconds after one party hangs up.

Rogers, which provides landline service in Ontario, New Brunswick and Newfoundland also has a delayed disconnect time of 10 seconds.

Bell, the parent company of CTV News, didn’t disclose any information about its disconnect times.

If you get one of those suspicious calls, hang up and wait 10 minutes or longer before using your landline, or you could use your cellphone.

The Canadian Anti-Fraud Centre also says it is also common for those fraud calls to come early in the day.

“You haven’t woken up, you haven’t had your coffee and you create that situation of urgency so you sort of get that emotion involved the panic the fear,” added Thomson.

In that instance, an immediate call to your bank could backfire.

“That’s what they always tell you to do if your card is lost, or stolen, or compromised is to call the number on the back but in this case it didn’t do me any good,” said Cerny.