Microsoft has announced their quarterly financial results for the period ending September 30th (fiscal Q1 2015), posting $5.48 billion in operating income and $4.5 billion in net income on the back of $23.2 billion in revenue.

Compared to the same period last year, Microsoft's overall revenue has increased by 25%, although net income is down 14%. In the company's financial report, they lay the blame for lower income on $1.14 billion of "integration and restructuring expenses" relating to the acquisition of Nokia's Devices and Services business.

The good news for Microsoft is that their Surface division performed strongly, posting an increase in revenue of 127% on the same period last year. Thanks to the success of the Surface Pro 3, the division posted $908 million in revenue with positive gross margin, and is on track to be Microsoft's next billion dollar business.

The recently-acquired Lumia division is doing well, with Microsoft selling 9.3 million handsets in the quarter, a 6% increase on fiscal Q1 2014. Microsoft also revealed they have sold 2.4 million Xboxes this quarter, although they didn't specify how many of those were Xbox Ones.

As for other divisions, Microsoft's server group revenue jumped 13%, while commercial cloud revenue rose by a huge 128%. More people are now subscribed to Office 365 as well, while Windows volume licensing revenue increased by 10%.

With Microsoft set to launch Windows 10 next year, the company's next 12 months will be critical if they are to see further growth.