Hospitals are still reliant on "archaic" fax machines with thousands still in use, a survey shows.
Senior doctors said the continued use of the outdated technology was "ludicrous", and modern forms of communication were urgently needed.
The poll, by the Royal College of Surgeons using freedom of information laws, revealed nearly 9,000 fax machines were in use across England.
Newcastle upon Tyne NHS Trust topped the list, relying on 603 machines.
"Alongside innovation like artificial intelligence and robot-assisted surgery, NHS hospital trusts remain stubbornly attached to using archaic fax machines for a significant proportion of their communications. This is ludicrous," said Richard Kerr, chair of the Royal College of Surgeons' Commission on the Future of Surgery.
"The NHS cannot continue to rely on a technology most other organisations scrapped in the early 2000s," he added.
Three-quarters of the trusts in England replied to the survey* - 95 in total. Barts Trust, England's biggest trust, uses 369 machines. Ten trusts said that they did not own any fax machines, but four in ten reported more than 100 in use.
The survey follows a report last year by artificial intelligence company DeepMind Health which named the NHS as the world's largest purchaser of fax machines.
Separate figures last year showed that the NHS is also heavily reliant on pagers. The report, by digital company CommonTime, said there were around 130,000 pagers in use at annual cost of £6.6m. The report emphasised that pagers were not only costly, but also limited, as they do not support two-way communication.
Faced with old-fashioned technology, DeepMind Health found that frustrated doctors had taken matters into their own hands and were using non-sanctioned apps like SnapChat and WhatsApp to communicate patient information.
The NHS has been slow to take on board the digital revolution. Back in 2013 then health secretary Jeremy Hunt, who left the department this week, said he wanted the health service to be paperless by 2018.
The new health secretary, Matt Hancock, who was appointed this week, is known to be a big supporter of digital technologies.
An NHS app allowing GP appointments to be booked and repeat prescriptions to be ordered, is due to be launched this year.
Some trusts are embracing new technology. At Oxford University Hospitals Trust, fax machines were switched off last year.
Chief information and digital officer Peter Knight said it was "one of the first" trusts to turn off its faxes and move to the internal email system called NHSmail.
He said the extra security requirements needed for patient data was one reason why the NHS had been slow to move away from fax technology.
Responding to the survey, Phillippa Hentsch, of NHS Providers, which represents hospitals, blamed a lack of funds for the over-reliance on outdated technology.
"For too long NHS capital spending on facilities and technology has been pared back in order to keep services going," she said.
"We see the results. Fax machines belong to the past."
Jason Zemmel, executive chairman of Integral Medical Holdings Group, a network which provides administrative support to the NHS, said modernisation was overdue.
"Whilst the service is starting to recognise the importance of technology, this highlights how far we still have to go to ensure that the NHS keeps pace with the complex, changing demands of patients in today's digitalised society."
*Surrey and Sussex Healthcare NHS Trust was originally included in this article as having 400 fax machines, but the Royal College of Surgeons has since admitted an error was made, and the trust only has one or two stand alone machines.