A US International Trade Commission judge, in a preliminary ruling, said mobile phones manufactured by Nokia and ZTE did not violate the patents of InterDigital.

The US-based wireless technology firm said it would likely appeal to the full commission, which is expected to issue its final ruling in October.

“While the investigation only involves a small portion of the wireless market, today’s decision by the Administrative Law Judge is unfortunate, and does not align with the validation of our portfolio and licensing practices that is reflected in our numerous agreements with major wireless companies worldwide,” said InterDigital in a statement.

“We will evaluate our course of action once the detailed decision is available, but it is likely that we will petition the commission for review and, if necessary, appeal the case to the Federal Circuit, where two of the three patents in this case have seen favourable decisions.”

InterDigital had also sued Huawei and Samsung for infringement, but both firms decided to settle.

Microsoft, which completed the acquisition of Nokia’s phone business in April, takes on the liabilities of the case.