Nokia has filed numerous patent infringement complaints against Oppo. They include both patents, which are key to certain standards, and ordinary ones. They relate to connectivity, interface and security. Complaints have been filed in Europe and Asia.
In 2018 Nokia and Oppo signed a licensing agreement. Under its terms, Oppo was able to use certain patents owned by Nokia. At the time of signing the contract, its validity period was not disclosed, it was only known that the contract was long-term. It looks like it has expired. Nokia made an official statement that Oppo rejected the offer to extend the contract, but continues to use patented developments, so the Finnish manufacturer had to take legal steps. However, the company still hopes that a “more constructive” way of resolving the situation remains.