Amazon has confirmed its virtual assistant Echo speakers are coming to the UK and Germany.
Until now, the company sold its voice-controlled devices only in the US.
The machines can answer questions, control other internet-connected devices, build shopping lists and link in to dozens of third-party services including Spotify, Uber and BBC News.
Experts say they appeal to early adopters' sense of curiosity but tend to be a harder sell to others.
Amazon told a press conference in London that the devices would become available in the two European countries on 28 September.
The main Echo speaker will cost 149.99/179.99, and there is a short-term discount for Amazon Prime subscribers who pre-order the hardware before this weekend.
"[Echo's] been relatively successful in the US because it is so easy to use," said Jessica Ekholm from the Gartner consultancy.
"But for many the question remains: why would they want a smart home?"
Privacy campaigners have also raised concerns about the use of such listening technology.
Amazon has not disclosed any sales figures for the Echo.
The BBC understands that one of the reasons Amazon had waited until now to launch the speakers outside the US was to ensure they could handle local accents.
At present, the devices' main competition are smartphone-, TV- and PC-based virtual assistants, including Apple's Siri, Microsoft's Cortana and Google Now.
Google has also announced plans to sell an artificial-intelligence-powered speaker of its own later this year.
The UK and Germany are being offered two types of speakers:
- the original Echo - a cylindrical mono speaker fitted with seven microphones, which automatically starts listening when the user mentions Alexa - the name of its virtual assistant - or an alternative wake word
- the Dot - which resembles a hockey puck. It has a similar voice-activated microphone array to the Echo, but a much smaller speaker. It is designed to be linked to third-party audio equipment via Bluetooth or a wired connection, and is marketed as a way to extend Alexa into additional rooms
A third type of portable speaker available in the US, called the Tap, was not mentioned at the press conference.
The Dot will cost 49.99/59.99 and can be bought at a discount if ordered as part of a six-pack or 12-pack. It will be released on 20 October.
Last week, one of Siri's inventors, Babak Hodjat, said Echo's lack of a screen or other visual feedback - apart from glowing blue lights - left owners with an "incomplete" experience.
But one industry-watcher suggested there were benefits to relying solely on voice.
"The smartphone app hasn't been a great interface for this type of thing," said Michael Philpott, from the consultancy Ovum.
"You've got to get it out of your pocket and then launch the app - which isn't the most user-friendly experience.
"If you can just say to Echo, 'Can you check if I've locked the back door?' that's much more natural.
"But of course, you'll also need to own smart door locks, and businesses are still trying to make the case for such smart home products to consumers."
For now, the most common smart home device is the thermostat - and the Echo can be used to control most of the leading brands, including Nest, Hive and Ecobee.
The speakers can also be used to play music, stream news broadcasts, read audio books, request car pick-ups and provide weather forecasts, among more than 3,000 so-called skills.
New additions include:
- News summaries from Sky News, Sky Sports, the Guardian and the Telegraph
- Travel updates from Network Rail
- Recipes from a Jamie Oliver-branded service
In addition, they can be used to order goods from Amazon itself, and will suggest items an owner has previously bought as well as goods that have positive ratings on its site.
"Amazon has an early mover advantage," said David Watkins, from Strategy Analytics.
"One of the difficulties of using this type of product in its early stages is that the user still has to memorise quite a lot of commands to make it function correctly.
"But over time, Amazon should be able to analyse the data it collects to find out what people like to say and what seems more natural to them.
"So, as the product matures it should understand more context and language, and become capable of more personalisation. And that, in turn, will make it appeal to more people."
The speakers are deliberately designed not to send data back to Amazon's servers unless there has been a wake command or button press.
Owners also have the option of deleting transcriptions and recordings of past voice commands via an app.
Amazon's device chief Dave Limp said privacy had been built into the products "from the start".
Even so, campaigners still have concerns.
"Devices such as Amazon Echo paint a detailed picture of who we are as individuals, which ostensibly Amazon then has access to," said Christopher Weatherhead, a technologist at Privacy International.
"For example, if we ask Echo about sensitive medical symptoms, we are potentially revealing very personal details to a corporation, which is not directly telling us how they use that data.
"It is crucial that should this data ever be requested by law enforcement, courts, or intelligence agencies, the strongest safeguards are in place to mitigate against the misuse of such information."
Until now, Amazon has not included details of law enforcement requests for Echo data in its bi-annual Transparency Report.