Qualcomm has accused Apple of stealing modem-chip designs and giving them to Intel in order to help Intel make cellular chips that could be used in iPhones at lower prices than those charged by Qualcomm.

“Apple has engaged in a years-long campaign of false promises, stealth, and subterfuge designed to steal Qualcomm’s confidential information and trade secrets for the purpose of improving the performance and accelerating time to market of lower-quality modem chipsets, including those developed by Intel Corporation, competitor of Qualcomm, to render such chipsets useable in Apple iPhones and other devices, with the ultimate goal of diverting Qualcomm’s Apple-based business to Intel,” Qualcomm wrote in a proposed amended complaint.

Apple started switching from Intel to Qualcomm modem chips in iPhones and other devices in 2011 when it launched the Verizon version of the iPhone 4, Qualcomm said. But Apple began switching back to Intel chips in some iPhone models in 2016, apparently to get lower prices despite the Intel chips’ lower performance. Qualcomm alleges that the switch to Intel in 2016 and Intel chip improvements since then were aided by Apple’s illegal actions.