STOCKHOLM (Reuters) -KPN NV, the largest Dutch telecommunications company, has filed a patent-infringement complaint against Ericsson in a district court in Texas, the Swedish telecom equipment maker said on Thursday. The issue revolves around Ericsson’s alleged infringement of five KPN patents covering various wireless network functions. In a court filing, KPN said it had offered to issue licences to Ericsson for the infringed patents but the Swedish company did not obtain a licence. “We refrain from making any further comments since this is an ongoing legal matter,” an Ericsson spokeswoman said. Lawsuits over royalty payments are not uncommon in the technology industry. Ericsson in December filed here a lawsuit in the United States against Samsung in a patent dispute. Ericsson had warned that delayed royalty payments and potential legal costs could reduce its operating income by 1-1.5 billion Swedish crowns ($118 million-$177 million) per quarter beginning in the first quarter of 2021. KPN has been a telecom equipment customer of Ericsson for more than a decade and last year awarded here the company a contract to build core elements of its new 5G mobile network. The Dutch company said in the lawsuit that it is seeking monetary compensation for the infringed patents. A KPN spokesman declined to give more detail as the case had been filed with the court.