Apple’s (s AAPL) iPhone stayed in high demand at AT&T (s T) during the first quarter of 2012 (ended March 31,) the company reported early today. The operator sold 5.5 million smartphones of which 4.3 million were iPhone activations. Of the iPhone activations, AT&T says a whopping 21 percent were net-new additions. In comparison, Verizon (s VZ) activated about 3.2 million iPhones during the first quarter of 2012. The demand for the iPhones is up year over year. During the first quarter of 2011, AT&T had 3.6 million activations while Verizon had 2.2 million activations.