Remember way back in 2010 when only AT&T customers could buy the iPhone? Oh, how times have changed. In the February of 2011, Verizon started selling the iPhone 4 and Sprint joined the party this past October by adding the new iPhone 4S to its lineup. T-Mobile remains the only national carrier not to stock the iPhone. The first weekend of sales topped 4 million iPhone 4S devices, thanks in large part to the buzz surrounding the very intelligent Siri voice-controlled assistant.