Nokia sues Apple as patent dispute becomes bitter

Nokia sued Apple saying the iPhone maker infringed several mobile patents, turning simmering tension between the companies into a bitter public legal battle.

The Finland-based company said Apple agreed to license patented inventions in 2011 but has refused to extend those expiring agreements. Nokia filed complaints with the German Regional Courts in Dusseldorf, Mannheim and Munich, and in federal court in Texas.

The dispute is rooted in Nokia’s demise as the world’s largest phone maker. Since selling its handset business, the company has focused on networking.