Echo, selling for $179 (roughly Rs. 11,390), is a voice-activated device which can "fetch" music or news, control home automation such as lighting and temperature and order products from Amazon.
"The customer response to Amazon Echo has been incredibly positive, and we've been working hard to build more as quickly as possible," Amazon vice president Greg Hart said in a statement.
"We are grateful to our early customers for their incredible engagement and for providing us with invaluable feedback to help shape Echo as it evolves with their help, we've been able to add features like Audible (audio books), Pandora, home automation, sports scores, calendar, and more."
The cloud-based brains referred to as "Alexa" are built into Echo speakers and seen as a challenge to "Siri" virtual assistants in Apple's coveted mobile devices.
A ring of microphones built into can-shaped Echo speakers enable the devices to identify voices even when music is playing, according to Amazon.
Echo accesses news, weather, streaming music and more using wireless Internet connections.
Echo can also be managed remotely using free applications built for smartphones powered by Apple, Android or Amazon's Fire operating software.
Amazon earlier this month insisted on a significant change to proposed US drone regulations before it introduces 30-minute Prime Air parcel delivery by unmanned aerial vehicles to its American customers.
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