It's a longstanding, and obviously false, rumor. It would be trivial to prove that these things connect to open wifi networks to phone home, but no one has ever proved that they do that, because they don't actually do that. It would be a little harder, but still very easy, to prove that they connect to cell networks, but no one has proved that they do that either, because they don't actually do that either.

Keeping them disconnected from wifi is sufficient.

You're all over this thread posting this same thing but you admitted that to you, "trivial" means substantial reverse engineering.

"Trivial" to me means looking up the FCC ID of the device and seeing what kinds of RF emissions it is supposed to radiate.

Or, still trivial (but more expensive): Point a spectrum analyzer at it and see what kinds of RF emissions it actually radiates.

I don't need to open the box to understand what kinds of noises it makes.

Or even just realize that if the devices had this capability these companies couldn't resist using it to show you ads. Since these devices don't show up to date ads unless you manually connect them to a network you can be reasonably sure that they don't have a fallback internet connection.

In the good old USA everything is legal until Congress makes a law, and Congress shall make no law. In the EU it's illegal.

It’s perfectly legal to put a cellular modem in a TV, but not without disclosing that to the FCC and on product labels. This and the mesh network thing for TVs are (currently) a conspiracy theory, which sucks because it muddies the waters in advance of it inevitably happening in reality.

Cellular modems seem unlikely, because both they and the service plan they'd need are too expensive to be justified by any benefit to the manufacturer.

Cell plans are very cheap when you are a company looking for low bandwidth off-peak service for a lot of devices. As individuals you can't get those deals, but companies can.

I don't know if TVs have a cell modem, but it isn't unreasonable to say they could.

As a different poster mentioned, the FCC needs to know about this though and so it will be documented.

Not so far fetched when your advertising revenue is in the tens of millions of dollars.

They just need this revenue by tv to be higher than the price of the mobile plan per tv. For a few Gb per month it may be relevant in the not so distant future.

Yes. Considering 90%+ of users will just connect their TV to their WiFi, shipping a cell modem with every TV to catch that last 10% seems like bad ROI.

I could however see this happening in the future in response to regulation. For example some "think of the children" rule that makes TV makers responsible for blocking mature content.

Phones already have modems that do Wi-Fi, cellular and Bluetooth in a single chip.

It may at some point no longer be economical to manufacture a Wi-Fi only modem.

I doubt the modem would cost more than $5 at scale. No idea what sort of off peak data deals you could get at scale but I have to imagine it’s close to being feasible.

You can get special IoT cellphone plans in bulk for something like $1 per device per month, or even less.