Banks are calling for access to clients’ phone data to see if their lines are busy when they are making big money transfers, in an effort to prevent fraud.

If banks find a client is on the phone while making a big transfer it could mean they are being scammed by someone impersonating a bank worker. According to the banks, 75% of all scam transactions are done while clients are on the phone with the fraudsters.

Access to this type of information would violate privacy rules but, Dutch banking association NVB and telecom companies said, a change to telecom rules could prevent scams from taking place.

“If the line is busy it may be a clue that fraud is being perpetrated,” NVB spokesman Jelle Wijkstra told broadcaster NOS. “We can then look and see if more things point to fraud and then stop the transfer until we are in contact with the client. We will ask them to make sure they are not being conned before we put the payment through.”

Older people in particular are often targetted by criminals and tricked into parting with their bank cards or making big transfers to so-called safe accounts by fake bank workers. Banks sometimes compensate for the loss but are becoming more reluctant to do so.

In Britain, experiments are underway with a system known as “scam signal”, which allows banks to carry out real time analysis and find links between phone calls and potentially fraudulent bank transfers.

A three month experiment by Vodafone and one British bank led to a 30% drop in successful scams, according to the Fintech Times.

The number of reported cases of bank helpdesk fraud in the Netherlands fell 45% in 2023 to €28 million, but remains extremely stressful to victims, the NVB said.