The official launch of the iPhone 4s last Friday was marked by the debut of Sprint Nextel as the third U.S. carrier to market the iPhone to its wireless subscribers. Analysts believe that the iPhone will provide Sprint—which lost 264,000 contract customers between June 2010 and June 2011—with a much needed competitive boost against market leaders Verizon Wireless and AT&T. Sprint’s entry into the iPhone carrier club leaves T-Mobile USA as the only nationwide wireless operator to lack access to the coveted device. (Contingent upon the completion of T-Mobile’s merger with AT&T, T-Mobile customers may eventually gain access to the iPhone although there is much uncertainty surrounding the AT&T/T-Mobile merger plan owing to the pending Justice Department and Sprint lawsuits against that deal.) Commenting on Friday’s launch, Sprint product chief Fared Adib boasted that his company “reported its best ever day of sales in retail, web and telesales for a device family in Sprint history.” Meanwhile, as Sprint customers queued up for the iPhone, Apple, Inc. confirmed that it has licensed C-Spire Wireless (formerly Cellular South) as the first regional U.S. wireless operator to offer its customers the iPhone. C-Spire, which serves one million customers throughout Mississippi, Tennessee, Alabama, and Florida, ranks as the eighth largest wireless carrier in the U.S. Although Apple did not specify an exact date, the company said on Tuesday that C-Spire would begin marketing the iPhone within a matter of weeks.