Nokia may have agreed to sell its handset unit to Microsoft but the Finnish phone maker held on to its valuable patent portfolio. The Finnish company could try to boost royalties by suing Android phone makers or unload patents in a future deal according to an ET report.

Nokia was once the most dominant handset manufacturer in the world. The company had failed to close the lead opened by Apple and Samsung in the smartphones' competitive market. The Finnish firm agreed to sell its handset division to concentrate in its networking equipment unit, navigation business and technology patents.

Last Tuesday, Microsoft agreed to pay EUR3.79 billion for Nokia's handset unit. Another EUR1.65 billion was paid for the 10 year license for the patents of Nokia. The payment for the company's patents was considered to be among the highest quality patents paid in mobile space.

Nokia had been a savvy player in the intellectual property market. In 2009, it had sued Apple and reached a licensing deal with the iPhone maker. The terms of the deal were not disclosed but believed to be worth more than USD100 million.