A federal jury on Thursday found Apple guilty of infringing on smartphone call handling and camera patents held by a licensing firm in which rivals Sony and Nokia hold stakes.
A verdict form available online showed that a trial held in the state of Delaware resulted in jurors finding that technology built into the iPhone violated three patents held by MobileMedia Ideas.
MobileMedia filed suit against Apple in early 2010, accusing the Cupertino, California-based company of infringing on more than a dozen of its patents but the number was trimmed to three by the time the case went to trial.
A date had yet to be slated for the portion of the proceedings that will be devoted to determining how much Apple should pay in damages.
MobileMedia's website described the company as a "patent portfolio licensor" of inventions by makers of smartphones and other mobile gadgets.
The company claims to have more than 300 patents in its portfolio, which is reportedly rife with technology innovations from Nokia and Sony.
Courtrooms around the world have become active battlegrounds for "patent wars" being fought by smartphone titans.
Apple recently negotiated a truce with Taiwan-based HTC, but remains entrenched in legal fighting in several countries with South Korea's Samsung.
Last week, a US judge mulling whether to trim or overturn Apple's billion-dollar damages award against Samsung in Silicon Valley called for a ceasefire in the ongoing patent war between the smartphone titans.
"I think it's time for global peace," US District Court Judge Lucy Koh said after legal teams from Apple and Samsung duelled for hours over post-verdict motions in her courtroom in the Silicon Valley city of San Jose.
"It would be good for consumers; good for the industry and good for the parties."