Thanks to blockbuster sales of the entry-level Lumia 520, Nokia recorded its best-ever quarter for Windows Phone sales, with 8.8 million units sold in the quarter ending September 30. The news comes as part of the firm's interim report for Q3 2013, during which Microsoft announced its intention to purchase Nokia's devices and services businesses.

"The third quarter was among the most transformative in our company's history," Nokia CFO and interim President Timo Ihamuotila said in a prepared statement. "We became the full owner of NSN [Nokia Solutions and Networks and HERE] and we agreed on the sale of our handset operations to Microsoft, transactions which we believe will radically reshape the future of Nokia for the better. Subject to the completion of the Microsoft transaction, Nokia will have a significantly improved earnings profile, a strong financial position, and a solid foundation from which to invest."

Now, not so much. Although the firm ended the quarter with over $12.5 billion in cash and cash-like assets, its devices and services businesses—the parts Microsoft is buying—were down 1.6 percent year-over-year. But net sales in the businesses were up 6 percent to $4 billion.

Nokia sold 8.8 million Lumia smartphones in the quarter, a jump of 19 percent quarter-on-quarter from its previous record-setting second quarter finish, when it sold 7.4 million units. More important, perhaps, the gain is even bigger year-over-year, which is how such sales are traditionally measured: In the same quarter in 2012, Nokia sold just 2.9 million Lumia smartphones.

Also good news: Nokia sold 1.4 million Lumia handsets in the United States, traditionally one of its softer markets. Although that's a relatively modest figure, it's also almost a 400 percent increase over the same quarter one year ago. In the first quarter of 2013, Nokia sold only 700,000 Lumias in the United States.

Nokia's Lumia-branded Windows Phone handset lineup surged, thanks largely to sales of the entry-level Lumia 520, which has been a global phenomenon responsible for recasting market-share numbers in key markets in Europe and Central and South America. The Lumia 520 is now the best-selling Windows Phone handset by far, and is also the best-selling Windows device, period, in the world.

(You can learn more about the Lumia 520 in the post "In Praise of the Nokia Lumia 520." It's one of the most versatile digital devices I've ever used.)

Nokia also sold 55.8 million Asha smartphones and Nokia mobile phones in the quarter, the firm reported.