Like two superpowers that cooperate for mutual benefit while eyeing each other warily, Nokia Corp. and Qualcomm Inc. have forged an uneasy alliance. Since the early 1990s, Qualcomm has reigned over the cell phone industry, licensing out the basic patents underlying the two main industry standards, GSM and CDMA. As the world’s leading cell phone manufacturer, with $50 billion in annual revenue, Nokia is one of Qualcomm’s most important licensees. The Finnish company has paid Qualcomm billions of dollars for the rights to so-called second-generation cell phone technology.

Now this fragile d�tente has reached a breaking point. In April the patent cross-license between the two giants is set to expire. The terms of that pact are confidential, but it is widely believed that Qualcomm collects an average of 5 percent from licensees of its CDMA cell phone technology. Nokia wants a better deal — and it’s not alone.