It was a man trying to break into her home that turned Jessica Randle into a leading advocate for video doorbells.

Ms Randle had been napping in her living room in Phoenix, Arizona, when she heard a slight noise from outside that she chose to ignore.

Later, when she reviewed the automatic recording from the video doorbell on her phone she discovered that a burglar had tried to open her front door. He then walked off, most likely after seeing the camera.

"I had been completely unaware, just completely oblivious," she says.

The incident inspired Ms Randle and her husband to start Doorbell News, a YouTube channel that curates interesting security footage caught by video doorbells across the US. Launched in 2017, its videos have now been viewed 397 million times.

Ms Randle is convinced that video doorbells, which are also called smart doorbells, make a significant difference in home security. "I feel like I can, you know, sleep safely in my home," she says. "And I can walk away from my home without being paranoid."

There is no doubting the ever-growing popularity of the doorbells. Some 11.7 million were sold around the world in 2021, up 63% from 2020, according to one estimate.

The doorbells connect to a property's wi-fi, and then to an app on the user's phone. So you can be away from home, and get instant notification and video footage of someone at your front door. You can also talk to the person.

The video recording is then typically stored on a cloud computer for a month, if the user pays a subscription.

But do video doorbells really improve your home security and help catch criminals?

"Like all CCTV, we use video doorbell footage as evidence to help solve crime," says a spokesman for London's Metropolitan Police.

He pointed to a case from May of this year, in which a man was convicted of manslaughter "after Met detectives pieced together the case against him via video doorbell footage".

A doorbell recording was also used last year to help convict a man in Somerset who had murdered his two next-door neighbours.

At Greater Manchester Police, officers now often ask people to submit doorbell camera footage to help investigations. The recordings are then used as evidence, or turned into stills to make public appeals to help identify suspects or find potential witnesses.

Meanwhile, a spokesman for the College of Policing, the professional body for the police in England and Wales, told the BBC doorbell video cameras are increasingly being used across all forces, and are having a positive impact.

The world's best-selling video doorbell is Amazon's Ring. Dave Ward, managing director of the Ring division, says: "We have taken home security to the next level, by really democratising the technology."

What he means by this is that the doorbells don't need to be installed or monitored by a professional company.

Google's Nest is another popular video doorbell. Rose Yao, Nest's vice president of product management, echoes the view that security is a key reason why consumers buy the products.

This includes keeping an eye out for so-called "porch pirates" – opportunist thieves who target deliveries left on people's doorsteps.

In the US, both Ring and Nest have provided footage to thousands of police forces across the country for a number of years.

However, this has not been without controversy, as there have been some occasions where Ring and Nest have given footage to US police forces without first getting permission from the homeowner.

Ring counters that it only does this "in cases involving imminent danger of death or serious physical injury to any person". Nest makes the same argument.

Another criticism of video doorbells is whether they infringe on the privacy of neighbours, whose comings and goings could be recorded by the motion-detecting cameras. In 2021 a judge in Oxford ruled that the use of a Ring doorbell broke data protection laws, and that a neighbour of the owner had been harassed by its use.

In response Ring urged users to check their camera's adjustable "motion zone", so that areas outside their property were not recorded.

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While footage from video doorbells is being increasingly used by police forces, do the products work as a crime deterrent in the first place? The evidence appears to be mixed.

Back in 2017, the Los Angeles Police Department said that, in a trial, the crime rate in an area with homes fitted with Ring video doorbells saw a 50% reduction in crime compared with another neighbourhood that did not have the cameras. Yet since then other police forces have said that the doorbells make little difference.

Meanwhile, UK organisation Centre For Research And Evidence On Security Threats says that video doorbells may actually make a home more vulnerable to being burgled. Its argument is that the doorbells indicate to a burglar that the homeowner is affluent, and therefore is likely to have things worth stealing.

Separately, last year Ring had to fix a weakness on its phone app, after security researchers discovered that hackers might be able to access video recordings.

Stacey Higginbotham is the editor of the Internet of Things podcast, and an expert on video doorbells.

"From a physical security perspective, I really don't know how much good these doorbells do for people," she says. "You can now [for example], watch someone take your package. A lot of times robbers realise that they're there now, so they either have a hat covering their face, or they look away from the doors when they're taking it."

Ms Higginbotham adds that while she is pleased that footage is being used by police forces, she worries about the larger application of this. "It opens up this entire network of surveillance where there hasn't been on before.

"And it's not clear if we have the laws in place to protect civil liberties while these are being used and deployed widely."