WASHINGTON - In the latest round of patent infringement lawsuits, technology giant Microsoft has lost the preliminary ruling to InterDigital, Inc., a Nasdaq listed wireless research and development company, in a case that could lead to a ban on Nokia and Microsoft mobile phones imports into the US.

Administrative Law Judge Theodore Essex of the U.S. International Trade Commission ruled on Monday that Nokia and Microsoft Mobile products infringed two patents held by InterDigital.

Essex's decision is preliminary and will be reviewed by the full commission. The ruling covers most of Microsoft's mobile phones, according to InterDigital spokesman Patrick Van de Wille.

Microsoft acquired Nokia's devices business last year.

The patents in the case cover technologies involved in powering up a phone and having it connect to 3G wireless networks. Even though most current cellphones use 4G LTE, they still have 3G capability for use where 4G isn't available.

InterDigital revealed on Monday that it has received a notice of the initial determination on remand by the Administrative Law Judge in US International Trade Commission investigation that besides Nokia and Microsoft Mobile products infringing two InterDigital patents, there is no evidence that InterDigital has engaged in "patent hold-up".

The probe has also established that there is evidence of "reverse patent hold-up" by one or more of the Nokia and Microsoft Mobile respondents in the case.

"Reverse patent hold-up" generally refers to implementing standards-based technology without being genuinely willing to obtain and pay for a license on FRAND (fair, reasonable, and non-discriminatory) terms and conditions to the owner of patents related to that technology.

"We're obviously very satisfied with today's ruling, which underscores the strength of InterDigital's portfolio and our long track record of developing and licensing some of the core wireless technologies that have helped drive the growth of our industry," said Lawrence F. Shay, Executive Vice President, Intellectual Property, and Chief Intellectual Property Counsel in a statement.

"We hope it will form the basis for the final determination by the ITC. We also look forward to continued discussion with Nokia and Microsoft Mobile to achieve a license on fair and reasonable terms."

In the 613 Investigation, first filed in 2007, InterDigital had sought an exclusion order prohibiting the importation into the United States of Nokia and Microsoft Mobile devices with 3G WCDMA capabilities that infringe two of its patents.

In 2013, the 613 Investigation was remanded to the ITC from the U.S. Court of Appeals for the Federal Circuit, which held that the Commission had erred in interpreting certain claim terms in InterDigital's patents.

Those erroneous interpretations, which led to the Commission's finding of no infringement and therefore no violation as to the two patents that were the subject of the appeal, were reversed. The ITC's final verdict in the investigation is expected by August 28.

Microsoft downplayed the significance of the preliminary decision.

"This is one step in the process and we look forward to the full Commission's thorough review," the company said in a statement. "We have a successful track record challenging patent assertion entities that misuse industry standards."