The anticipation on Apple's upcoming smartphone releases, the iPhone 5S and the iPhone 6, is fast building up that could translate to incredible sales surge for the iOS 7 devices by the end of the year, a new report said.

The Apple mobile phones are now the subject of gadget-buying plans by majority of teenagers in the United States, a new Fortune report said, citing the statistics provided by analytic firm Piper Jaffray.

As many as six out of ten American teenagers are harbouring plans to get the iPhone 5 refresh and Apple's rumoured phablet once the devices become available, which analysts said will happen between August 2013 and January or February 2014.

Up to 62 per cent of U.S. teens will buy an iPhone anytime this year, the Piper Jaffray survey said, many influenced by the rousing success of the iPhone 5 in the North American market, which remains as the biggest and most lucrative smartphone market to date.

The year 2012 is also marked by the study as the busiest gadget shopping period for young smartphone users, with about 90 per cent mulling an upgrade to newer units.

Some 59 per cent of the youngsters surveyed shared their desire to buy new handsets that is run by the iOS 7 mobile platform. Another 21 per cent has indicated that they're choosing Android phones, with the option likely dominated by Samsung's Galaxy smartphones such the Galaxy S4 and the Galaxy Note 3.

The relevance of the new study was backed by an earlier report which confirmed that teenagers play a big role in the spending decisions of their parents, Gotta Be Mobile said in a separate report.

In a given year, kids can prod their parents to splurge $5,000, with mobile phones occupying notable slots on the shopping lists.

And good for Apple, its iPhones remain as the choice of gadget for most U.S. teenagers, many of whom would end with new gizmos anytime on the second half of 2013, the same GBM report said.