It wasn't dropped fly balls or kicked grounders that drove some Phillies fans crazy last fall during the World Series games at Citizens Bank Park.

It was AT&T Inc.'s overloaded wireless network in South Philadelphia that, if it didn't actually drop a voice call, wouldn't easily let iPhone users use e-mail, send text messages, or connect to the Internet during the sold-out and dramatic championship games.

Phillies fans howled, and now AT&T says it got the message: the company plans to upgrade the ballpark for this baseball season, which began Monday for the Phillies in an 11-1 win over the Nationals in Washington.

The upgrade is part of a national program at AT&T to boost wireless capacity in sports arenas and other public venues, said AT&T spokesman Adam Cormier. The Texas company, one of the nation's largest wireless providers, is the exclusive network for iPhones, which are popular with users, but also tend to be data hogs. Some analysts say that if AT&T does not boost its wireless capacity, unhappy customers will look for a new wireless provider.

AT&T will wire the inside of the Philadelphia baseball park with about 100 antennas to catch iPhone calls and route them to high-speed terrestrial data lines so that the calls do not have to travel to one of four cell sites outside the ballpark in South Philadelphia, officials say.

The new technology is the same as that used in hospitals and airports, along with Yankee Stadium. During a sold-out Phillies game there could be 5,000 to 10,000 iPhone users in the ballpark, according to industry estimates.

"We're laying it on pretty thick," Roger Doub, AT&T's operations manager for network services in the Philadelphia area, said recently outside the ballpark. He spoke on the roof of the Holiday Inn on Packer Avenue, a cell site for the ballpark and stadium parking lots.

Phillies spokeswoman Deanna Sabec said Wednesday that AT&T was negotiating with the stadium for the upgrade. Thus, it will not be ready for the Phillies home opener Monday against the Nationals.

"It will happen, but we can't give out any details because nothing has been signed," Sabec said.

The popularity of the Phillies and some other baseball teams in big-market stadiums are special problems for AT&T. Baseball fans have time to use the iPhone because of the slow pace of the game and the fact that they do not have to be glued to the action every minute. Said Doub: "You don't go to a ball game just for the hot dogs and beer anymore."

Contact staff writer Bob Fernandez at 215-854-5897 or bob.fernandez@phillynews.com.