Android remains the most popular operating system in the world. However, after the latest sales numbers it appears the Google powered OS doesn't have the same sized lead in the market that it once did.

Android took home 52 percent of all U.S. smartphone sales from March through April, which is almost no gain compared to the same period last year, according to Kantar World Panel.

Meanwhile iOS grabbed 41.9 percent of the smartphone sales market in the United States, an increase from 3.5 percent from this time a year ago. According to CNET, Apple has T-Mobile to thank for a lot of the gain.

The iPhone 5 was the top selling smartphone at T-Mobile over the three month period between April and May that it sold through the mobile retailer. It was a popular item amongst T-Mobile users who wanted an entry into the smartphone market.

According to Kantar, among all T-Mobile subscribers who purchased an iPhone from March through May, 53 percent upgraded from a feature phone. The average iPhone buyers who make a similar switch on average is roughly 53 percent. Furthermore, Apple is likely to get more out of it's partnership with T-Mobile in the future. Among subscribers who plan to change their phones over the coming year, roughly 28 percent of them say they are eyeing the iPhone 5.

Meanwhile, Windows Phones remain in third place among U.S. smartphone sales with only 4.6 percent. However, it is up almost 1percent from the same time  in 2012.

Right now the iPhone 5 is the top-of-the-line smartphone from Apple. Unconfirmed rumors speculate that the newest incarnation of the iPhone is likely to be the iPhone 5s, but that isn't expected to reach consumers until this Septemebr at the earliest. In any case, the new phone coupled with the new iOS 7 is expected to help Apple continue to grow in the smartphone operating system market.