Microsoft is handing its mobile, display and video advertising duties to AOL to sharpen its focus on software/hardware development.

It will transfer 1,200 advertising staffers to the online company that is being acquiring by Verizon in a $4.4B deal.

AOL will represent Microsoft brands such as MSN Homepage, Outlook Mail, Xbox, Skype and assorted apps in the US and eight markets.

It will use Microsoft's Bing search engine for its online properties, beginning Jan. 1 for a ten-year period

Bob Lord, AOL president, said the partnership "further validates our leadership position in digital advertising and the shift to automation, while also allowing Microsoft to focus on what they do best: industry leading services and search innovation."

Microsoft spent billions to develop its advertising capabilities. Former CEO Steve Ballmer in 2006 called advertising staffers vs. software developers "the backbone of the company."

CEO Satya Nadella, who took the Microsoft helm 17 months ago, has emphasized growth in the tech sector.

Verizon justified its deal with AOL as an opportunity to capitalize on its advertising technology savvy.