T-Mobile USA is taking steps to update their infrastructure, hoping that will be enough for Apple to award the nation’s fourth largest carrier with the iPhone this year or next, according to MacRumors.

The carrier announced yesterday plans to begin work with Ericsson and Nokia Siemens to roll out LTE service in 2013. In addition, carrier network improvements will allow them to offer HSPA+ service before the end of this year. Apple is expected to add LTE compatibility to their sixth generation iPhone, which should arrive later this year.

Although T-Mobile’s LTE service wouldn’t come online in time for this launch, adding HSPA+ network support could be just enough for Apple to announce T-Mobile as another U.S. iPhone carrier later this year, or in 2013 at the latest.

In March 2011, AT&T announced plans to purchase T-Mobile USA. However, by December, the deal was dead after the U.S. government rejected it. Since then, a number of U.S. regional carriers began selling the iPhone, but not T-Mobile. To date, Apple’s handset is available at Alaska Communications, Appalachian Wireless, AT&T, Cellcom, C Spire, GCI, nTelos, Sprint, and Verizon Wireless.

If T-Mobile were to offer iPhone service, would you switch from one of the other carriers?