Microsoft (MSFT) is expected to layoff hundreds of people as part of a company wide restructuring of its marketing operations reports Bloomberg.

It not known exactly how many people will be let go but the cuts will start within the next 30 days according to Bloomberg’s sources. Microsoft Chief Executive Officer Steve Ballmer doesn’t think the company is getting enough return on the billions it spends annually on marketing, the sources said.

The cuts would eliminate overlap in job responsibilities and are designed to help the company better respond to threats from Apple (AAPL), Google (GOOG) and Amazon.com (AMZN), which are increasingly targeting Microsoft’s corporate-computing customers.

“The changes may include shifting some of the more technical marketing workers to engineering groups, cutting employees who don’t have needed skills or whose work is duplicated by other workers, and revamping how marketing groups are organized and where they fit into the rest of the company”, the sources told Bloomberg.

Microsoft spent $13.9 billion on sales and marketing in fiscal 2011, up 5.5 percent from the previous year. Microsoft said then that it had 25,000 workers devoted to those tasks, without breaking out how many are focused on marketing. The company had about 90,000 full-time employees in total.

Consumer-focused technology companies like Apple are making inroads in the business world, forcing the information- technology industry to regroup. Apple will sell $10 billion worth of iPads and $9 billion of Mac computers to corporate customers this year, a 58 percent jump, according to Forrester Research.

Microsoft also is facing rising costs because of a shift to cloud software, which is stored in the company’s data centers and delivered over the Internet. Its $8.5 billion purchase of Skype Technologies SA and Xbox gaming products are increasing expenses as well.