Apple isn't just holding onto the top spot among US smartphones with last year's iPhone 4. It's also occupying the second most popular slot with its budget priced iPhone 3GS, which is only available in the country on one carrier.

A report by NPD Group trumpeted the broad use of Android across 52 percent of phones sold to consumers in the US in the second quarter of 2011, noting only a slight quarterly gain by Apple to claim a 29 percent share.

Buried deeper in the data is the fact that Apple is holding its position and then some using two models at the end of their lifespan. The most popular US phone is Apple's relatively expensive iPhone 4 which was released over a year ago.

The two year old iPhone 3GS held onto the second spot in popularity thanks to its low price, which AT&T has used to compete against Verizon after its rival gained access to the iPhone 4 this spring. Initially $99, the model has been offered for $49, with occasional promotions that make the phone free with a contract.

Google has promoted its Android platform as having the potential to drive down the cost of hardware to attract low end buyers, but Apple's ability to sell older versions of its flagship iPhone at a discount has so far beaten Android at its own game.

Apple is expected to release a new iPhone 5 model around the end of September or early October, and is anticipated to similarly offer a lower end version of iPhone 4 as its budget-priced model.