That timeframe is significant. Although Apple's iPhone reached 100 million sold quite some time ago -- March of 2011 -- that was nearly four years after the introduction of the iPhone in the summer of 2007.
Samsung broke the numbers down somewhat. It's latest superphone, the Galaxy S IV, has reached the 40 million-mark in just seven months. Compare that to Samsung's prior flagship phone, the Galaxy S II. That phone also hit 40 million units in sales, but it took 20 months for that phone.
It's obvious that the Galaxy S line of smartphones is Samsung's most successful, and there is heightened anticipation about the Galaxy S IV. Some hoped that the IV would be unveiled at CES, but it was not to be. There is still Mobile World Congress in February, but Samsung has already shot down rumors of a reveal there.
Meanwhile, while not dishing on the Galaxy S IV, Samsung unveiled its Exynos 5 Octa eight-core processor at CES. It's expected the Galaxy S IV will sport that processor.
Don't think that Samsung is a one-hit (or one series) wonder when it comes to smartphones. The company previously announced that sales of its Galaxy Note (phablet) handset surpassed 10 million units, and thus far, there have been more than 5 million Galaxy Note IIs sold.