The online ads sound too good to be true.

"Say goodbye to your cable bills and get your TV for free," boasts an advertisement for the Free TV Box in Canada.

A U.S. company promotes its TV box as the "cable killer."

"You will have instant access to watch every episode of any TV show … and never pay a monthly bill!" promises the company's website.

Customers do have to pay for the device, which sells for around $100 to $200, depending on the model. But the promise of television without monthly bills is real, and it's a fast growing business.

Here's how it works: vendors start with a basic Android TV box. The devices are similar to Apple TV, but they use the Android operating system. That means vendors can load them with special software so the gadget can access an almost unlimited amount of television shows and movies.

Customers attach the loaded box to their TV and stream whatever they want, with no commercials. There are no monthly fees, just the up-front cost of the device.

The device could be a threat not only to cable companies but also to video streaming services.

"It works very similar to Netflix, except you get to watch whatever you want to watch," said Joel Adams, who sells loaded Android boxes online from his home in Hubbards, N.S.

"And it's free."

So, what's the catch? Turns out, legally, there might not be one in Canada, at least not yet. Yes, sometimes customers are watching copyrighted content, but they aren't downloading that material. They're streaming it, and streaming falls into a legal grey area.

"It's not illegal," claims Adams. "It's up to yourself to decide if it's immoral."

The free TV business

Adams runs his company, Astro TV Boxes Canada, as a side job, but he says business is so good, last month, he made more money peddling his boxes than working at his full-time job at a printing company.

"It's pretty amazing," he says of his product. "I guess that's why they sell so well."

The entrepreneur explains he orders Android boxes from China and then loads them with extra software and apps. His most popular model sells for about $120.

Adams says customers can use the device to access almost any current show or movie or ones that were popular in the past. He uses his box to watch popular shows such as Dr. Who, Game of Thrones and The Walking Dead.

"I haven't had cable in a long time," he said. One of the loaded Android boxes that Joel Adams of Nova Scotia sells online through his home-based business.

Adams explains the box's apps provide access to giant content libraries. The content comes largely from material people across the globe have uploaded and made available on file-sharing websites.

When a viewer types in a show title using the box and does a search, numerous links will pop up. The person then clicks on a link and streams the show. But, Adams cautions, not every link works.

"If it doesn't, you try the next one. You always find one that works eventually," he said.

Viewers can already access various free streaming services online — and could just connect their computer to a TV monitor — but Adams says the advantage of the loaded box he sells is that it consolidates a large amount of content in one place.

"It's just so much more convenient," he says.

'We even got rid of Netflix'

Jenna Galloway says the other day she watched the movie Zoolander 2 using her Android TV Box. The blockbuster is still in theatres in Canada.

She's also watching the latest season of the British show Call the Midwife, which actually won't air in Canada until the spring.

"It's crazy. It's already paid for itself," she said.

Galloway, who lives in Cole Harbour, N.S., says she cancelled her cable two years ago. She felt her TV bill was too high, so she signed up for Netflix instead.

But in September, Galloway had to go on two month's bed rest during her pregnancy, so she bought the box to fill the time. Now, she's says, it's all her family uses to watch TV shows and movies.

"We even got rid of Netflix," she admits.

"I don't know what we'd do without it."

Galloway says she's convinced many of her friends and family to also buy the box.

Is it legal?

As the loaded Android box business grows, so do the legal questions.

Many of the shows customers are watching are intended to be watched by paying subscribers to cable or streaming services that have struck distribution deals with the owners of the content.

Canada's Copyright Act prohibits unauthorized downloading of copyrighted content. But viewers using a loaded Android box are only streaming, not downloading material.

"Streaming falls a little bit into that grey area," said internet law expert Michael Geist.

That's because streaming video could be considered a "transient, temporary display," he says.

"It's called the Copyright Act for a reason, and, of course, there are questions as to whether or not a copy or infringing copy is even being made in a streaming context," said the University of Ottawa professor.

Copyright lawyer Ariel Thomas of the firm Fasken Martineau in Ottawa agrees. "Receiving a stream, in itself, isn't something targeted by the Copyright Act," she said.

She argues, however, that the loaded Android boxes could potentially run into trouble. That's because the law prohibits services that exist primarily for the purpose of "enabling copyright infringement."

But the Android boxes can also stream plenty of legal content, such as YouTube videos and Netflix shows.

Geist notes that the one party that is clearly running afoul of the law are the sites offering up the content for streaming.

"If they're doing so without authorization, they're infringing, and there is law that can address that," he said.

But many of the streaming sites operate outside Canadian borders.

CBC News asked the federal government to weigh in on the legality of streaming.

"Whether or not a specific website, app or service infringes copyright would be determined by the courts on a case-by-case basis," said Canadian Heritage spokesperson Simon Rivet in an email.

Will cable kill free TV?

Adams believes if anyone is successful at shutting down his business, it will be the cable companies.

"I'm sure they'll make some kind of move to counter this," he said.

That's why he's not quitting his day job.

Galloway also fears the day could come when loaded Android boxes are run out of business.

She says if that happens, she'll have no regrets because she's already gotten her money's worth.

"Even if I get a year out of it, even if I get six months out of it, it's worth it," she said.