Close to half of Apple iPhone users in the United States would be "very interested" in dumping AT&T for Verizon Wireless as a service provider, according to a study from professionals service firm Deloitte.

"If another carrier were to pick up the iPhone, you would probably see a number of defections," said Ed Moran, director of insights and product innovation at Deloitte.

AT&T Chief Executive Randall Stephenson played down the potential impact of the loss of iPhone exclusivity to Verizon or other companies at a Goldman Sachs conference on Tuesday.

Stephenson said about 80 percent of AT&T's iPhone users were either in family plans making it difficult to cancel service or had received their phone through their business.

"Those customers don't tend to churn," Stephenson said.

The Deloitte study also found that 55 percent of respondents said they are not very interested in purchasing the Apple iPad digital tablet.

But for existing owners of the iPad and other mobile devices, Deloitte found changes in the way they used the devices.

Some 41 percent of respondents said they used their smartphone as a replacement for their laptop or mobile device while away from home. Fifteen percent said they do the same while at home.

For the millennials — those surveyed between the ages of 14 and 27 — 31 percent said playing games on smartphones and other devices have cut the time they spend on video game consoles such as Nintendo and Sony PlayStation.

Social networking and game applications proved to be the most popular downloads for smartphones and mobile devices for all respondents, according to the study.

"It begs the question in terms of big trends what else will be cannibalized?" Moran asked.

The online survey, conducted between June 29 and July 11, asked 2,000 U.S. consumers between 14 years old and 75 years old about how they used their mobile devices.