Demand for the iPhone 4S among U.S. consumers remains "incredibly strong," a research company said today as it cited a late December survey of smartphone buying plans.

According to ChangeWave Research, 54% of the U.S. consumers who said they planned on buying a new smartphone in the next 90 days tagged Apple's iPhone 4S as their likely purchase.

While that number is down from the 65% who identified the iPhone as their preference just before Apple debuted the iPhone 4S in October 2011, it's the highest ever for an Apple smartphone two months or more after its introduction, said Paul Carton, director of research at ChangeWave.

"Apple has never dominated smart phone planned buying to this extent more than two months after a major new release," said Carton in an email Monday.

In September 2010, just months after the introduction of the iPhone 4, a similar ChangeWave survey put the purchase plans for an iOS-powered smartphone at just 39%, neck-and-neck with Google's Android . That number of 39% was the prior record for the iPhone's portion of planned purchases two or more months after the debut of a new model.

"The pattern is clear," said Carton in an interview Monday. "Apple has never had a score like this."

iPhone buying plans have followed a definite pattern. Historically, interest jumps just prior to the release of a new iPhone, peaks at or immediately after the release, then wanes.

In June 2008, for example, anticipated iPhone purchases reached 56% in a poll conducted the same month the iPhone 3G shipped, but fell to 34% three months later, then dropped to 30% before climbing again to 44% in mid-2009 when the iPhone 3GS launched.

The iPhone 4's trend line, however, was different: While that 2010 model peaked at 52% and then fell to 39% three months later, it jumped back up to 47% around the time that Apple started selling its smartphone to Verizon customers in early 2011.

"The Verizon effect was strong enough to bend the pattern," said Carton, "because a whole new class of users could have the smartphone. So now, the iPhone 4S is still doing its thing. It ain't over for the iPhone 4S."

In the most recent poll, the only smartphone maker other than Apple to register in double digits was Samsung, with 13%, an eight-point jump since ChangeWave's September 2011 survey.

U.S. consumers' plans to buy an iPhone are at an all-time high. (Data: ChangeWave Research.)

Carton attributed the spike in Samsung phone purchase plans to the Galaxy Nexus , the first 4G phone equipped with Android 4.0, or "Ice Cream Sandwich," which went on sale in the U.S. in mid-December. Carton called the Nexus "a major driving force" behind Samsung's numbers boost.

Samsung's jump was the second in the last 18 months: In September 2010, ChangeWave recorded a 600% increase -- from 1% to 6% -- among U.S. consumers who said they were going to buy a smartphone made by the Korean company.

"Then boom, Samsung took off again," said Carton of the eight-point increase from September to December 2011.

Not surprisingly, customers said they were happiest with Apple's and Samsung's smartphones. Seventy-five percent of iPhone owners said they were "very satisfied" with their purchase, while 47% of Samsung users said the same.

Apple fans also remain pleased with the iOS operating system that powers the iPhone, with 75% of owners agreeing that they were very satisfied with the OS. As in previous ChangeWave surveys, iOS trumped both Android (47%) and Microsoft's Windows Phone 7 (55%).

Microsoft has pinned much of its Windows Phone 7 hopes on its partnership with Nokia, but by ChangeWaves's survey, the Redmond, Wash. operating system developer has a hard row to hoe.

For smartphone makers, Nokia came in second-to-last in the customer satisfaction part of the poll, just ahead of the fast-dropping RIM. Twenty-three percent of Nokia owners said they were very satisfied with their purchase, while 22% of BlackBerry users loved their devices.

"There's a very strong correlation between satisfaction and buying plans," noted Carton.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer , on Google+ or subscribe to Gregg's RSS feed . His e-mail address is [email protected] .

See more articles by Gregg Keizer .

Read more about smartphones in Computerworld's Smartphones Topic Center.