Telecom equipment maker Ericsson has sued smartphone company Wiko to enforce its patents against Wiko’s infringing products.

Ericsson filed the patent case in the regional courts of Dusseldorf and Mannheim in Germany, for infringement of patents essential for 2G, 3G and 4G cellular technology, as well as implementation patents.

Ericsson said Wiko has been infringing Ericsson’s intellectual property rights for six years without any license or compensation. Ericsson has tried to establish a non-discriminatory (FRAND) license agreement with Wiko since May 2013, but has not succeeded.

“It is unfair for Wiko to benefit from our substantial R&D investment without paying a reasonable license fee for our patented technology,” said Gustav Brismark, chief intellectual property officer at Ericsson.

Ericsson has more than 42,000 granted patents. Ericsson’s patent covers 2G, 3G and 4G/LTE technologies. The Sweden-based telecom technology company plays a key role in developing standards for 5G technologies.