Samsung's Galaxy Note has shipped more than 5 million units since launch.
The Korean tech giant's hybrid device hit the milestone after just five months on the market, according to Engadget.
Samsung released the device in the UK in November last year. It had shipped more than 1 million units by December.
The Galaxy Note features a 5.3-inch HD Super AMOLED screen, the biggest of any phone currently on the market, and is powered by a 1.4GHz dual-core processor. A software update due in Q2 will upgrade its Android operating system from Gingerbread to Ice Cream Sandwich.
It also has an eight-megapixel rear-fitted camera with LED flash and a two-megapixel front-mounted camera. A pen-input technology called S Pen enables users to jot down notes and interact with certain applications.
Samsung's Galaxy Note is available in the UK across the major mobile networks, specialist phone retailers and key high street retailers.
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Watch a video introducing the Galaxy Note below: