SAN FRANCISCO: An iPhone 4S buyer has sued Apple for promising more than it delivered with automated "Siri" voice-activated assistant software built into the coveted smartphones.

A suit filed in a California federal court argued that Apple advertising touting the wonders of Siri amounted to "intentional misrepresentation" and unfair competition, according to documents available online Tuesday.

Lawyers representing a New York City man who bought an iPhone 4S want class action status to represent millions of people who bought the latest generation Apple smartphone.

The suit included Apple, which runs showing people asking Siri to help them find restaurants, learn chords to songs, tie neck ties, and even figure out if there is a rodeo in town, had disappointed some users.

Lawyers representing the iPhone 4S buyer, identified as Frank Fazio of Brooklyn, argued that Siri claims were "misleading and deceptive," and are calling for California-based Apple to pay unspecified damages.

"Promptly after the purchase of his iPhone 4S, plaintiff realized that Siri was not performing as advertised," the lawsuit said. "For instance, when plaintiff asked Siri for directions to a certain place, or to locate a store, Siri either did not understand what plaintiff was asking, or, after a very long wait time, responded with the wrong answer."

Apple does not comment on pending litigation.

Siri has been a hit since its US debut with the iPhone 4S in October and was even referred to as a direct challenge to Google's search engine by the internet giant's chairman Eric Schmidt.

Siri artificial intelligence software was derived from research conducted to make computers more intuitive at understanding and working with soldiers in action. Siri is designed to understand context so people can speak naturally when asking it questions.

For example, spoken queries of "Will I need an umbrella this weekend?" and "What is the traffic like around here?" will prompt online searches for local weather forecasts or road conditions.

Siri helps make calls, send text messages or email, schedule meetings and reminders, make notes, find local businesses, and get directions. Siri will even perform mathematical calculations if asked.