Helped by the iPhone, Verizon Wireless is pulling in more high-paying subscribers than it has in a year, and 15 times more than rival AT&T.

Verizon Communications Inc. on Thursday said it added 906,000 wireless subscribers on contract-based plans in the January to March period, more than double the number of a year ago.

The increase corresponds neatly with the half-million iPhones Verizon sold to new subscribers. Verizon started selling the iPhone on Feb. 10, ending AT&T's exclusive grip on the device in the U.S.

In total, Verizon said it had activated 2.2 million iPhones, with most of them going to customers upgrading from other Verizon phones.

Wall Street analysts had expected slightly more. Verizon shares fell $1.15, or 3.1 percent, to $36.63 in morning trading, retreating from a three-year high of $38.95 hit three weeks ago.

Verizon Chief Financial Officer Fran Shammo defended the iPhone sales performance on a conference call with analysts,

"We really weren't 100 percent out there with distribution until mid-March," he said.