Verizon Wireless has done a pretty good job fending off the iPhone, continually beating AT&T in terms of its net subscriber additions.

Until today.

Verizon Wireless fell behind AT&T in terms of net adds, adding just 1.2 million subscribers in its third quarter. In comparison, AT&T said last week it added 2 million subscribers in its most recent quarter and boosted ARPU nearly 4 percent to $61.23. Verizon’s ARPU slipped to $51.04.

AT&T’s success was widely attributable to the iPhone. The carrier activated a record 3.2 million iPhones last quarter, 40 percent of which were customers new to the carrier.

Verizon has no such magic bullet just as yet, but is moving aggressively to beef up its device portfolio with upcoming launches of the Motorola Droid and the BlackBerry Storm 2. It also has partnered with Google and expects to launch another Android-based device before the end of the year.

The hyper-competitive prepaid market also took a chunk out of Verizon’s earnings. Though Verizon is a postpaid shop, wide-ranging contract-free offerings from prepaid carriers have become more of an issue. Verizon has taken some steps to address encroachment on the lower end of its market, with TracFone Wireless selling service over its network under the Straight Talk brand.

There were some bright spots. Verizon’s data revenues grew significantly and now comprise more than 30 percent of all service revenues. Last year, data comprised just 25 percent of all service revenues. In addition, Verizon is still the champ when it comes to its wireless subscriber base, which now stands at 89 million customers compared with AT&T’s 81.6 million customers.

Overall, Verizon made $1.18 billion, or 41 cents per share. That figure marks a 30 percent decrease from last year, when the carrier made $1.67 billion, or 59 cents per share.