Activations of Apple’s popular iPhone 4 handset slowed significantly at Verizon Wireless last quarter. The nation’s No. 1 carrier reported its second-quarter earnings early Friday morning, at which time it revealed its latest iPhone numbers. Verizon Wireless activated 2.3 million iPhone 4 units in its June quarter for an average of just under 177,000 phones each week. In the first quarter, Verizon Wireless activated 2.2 million iPhones, but the device had been available for just seven weeks in the quarter. During that period, the carrier was activating an average of more than 315,000 devices each week. It stands to reason that iPhone 4 sales would slow following the device’s debut with the carrier, but this 44% drop off is a bit steep for the single most popular smartphone on the planet. AT&T announced on Thursday that it activated 3.6 million iPhones in the June quarter, but the carrier does not separate iPhone 4 and iPhone 3GS activations so there is no basis for comparison.