AT&T (s T) says that it added a total of 678,000 net wireless subscribers during the three months ending September 30, 2012 . It also reported 4.7 million iPhone activations, with 18 percent new to AT&T. Due to supply constraints, the company says that a “vast majority of third-quarter iPhone sales [were] going to existing customers to satisfy pent-up demand.” Wells Fargo Securities analyst Maynard Um in a note to his clients this morning pointed out that the “iPhone 5’s represented about 1.3mn or 28% of activations based on AT&T’s comments.”

He also pointed out that  together, Verizon and AT&T activated about of 7.8 million iPhones, versus 4.7 million last year and 6.4 million in the second quarter. That accounts for about “30.6% of our total iPhone units of 25.5 million” he added. Verizon (s VZ) in comparison activated 3.1 million iPhones. AT&T says that during the quarter it saw smartphone sales of 6.1 million and now has a postpaid smartphone customer base of 44.5 million, up 1.4 million from second quarter 2012.