AT&T’s report that they only received 146,000 iPhone activations on the first few days should be taken with a grain of salt.
The iPhone was released on at 6 PM on June 29, which means there was less than two full days before the end of the quarter. Some people may not have activated their iPhones right away. Since there were widespread reports of problems with activation, there may have been a huge number who simply weren’t able to activate within the first two days.
The actual sales numbers were certainly a lot higher than the number of activations, since most AT&T stores sold out the first weekend.