Siri, the sultry-voiced do-it-all software assistant for the iPhone 4S, might be responsible for a flood of traffic hitting wireless networks.

That could pose problems for consumers constrained by monthly data limits and wireless carriers trying to prevent dropped calls and sluggish service under the weight of smartphones and tablets.

Apple’s latest iPhone 4S is using three times as much data as the previous version, according to a study by networking software firm Arieso. Users of other devices such as the HTC Desire and Samsung Galaxy are also accessing the Internet more often to watch videos, browse sites and stream music.

But the iPhone 4S, whose biggest improvement was the introduction of voice-command service Siri, is turning consumers into extreme Internet users, according to Arieso. And Siri’s effect highlights the potential conflict between carriers, which want to limit customers’ access to their increasingly burdened networks, and Silicon Valley innovators, who want to feed new products to the Web-consuming public.

“While there is no question that hungry users are attracted to the iPhone 4S, the device appears to unleash data consumption behaviors that have no precedent,” Arieso said in a report about smartphone data consumption released Friday.

That's because the service makes it easier to use the Internet more often. To find a sushi restaurant nearby, a smartphone user typically has to fire up an app, type a search request and scroll through results. With Siri, that search is done by simply asking: “Find me a sushi place nearby.” And because of the way Siri operates, people are constantly online as the service roams the Internet to find answers.

The service might be easier for consumers but can be harder on networks, analysts say. With all major wireless carriers offering Apple’s iPhone, they all risk the kind of congestion that frustrated early iPhone users on AT&T, Apple’s first network partner.

Verizon said Friday that it sold 4.2 million iPhones in the fourth quarter, more than double its iPhone sales in the third quarter. Apple did not immediately respond to a request for comment.

“This suggests that the spectrum crunch may arrive sooner than people expected,” said Paul Gallant, an analyst at Guggenheim Securities. “It puts more of a premium on Congress doing what it can to put more spectrum into the market.”

That could specifically mean a better shot at legislation passing this February, attached to a payroll tax cut bill, that would free up airwaves for auction, Gallant said.

The White House and Federal Communications Commission have pushed for the auctions of airwaves, which they project will raise nearly $28 billion to be used to reduce the deficit. Critics say they aren’t sure broadcasters would be willing to sell spectrum currently under their control or if such sales would raise as much as projected.

The sharp increase in data use could result in higher cellphone bills, consumer advocacy groups say. Most carriers have adopted tiered data plans that charge more for greater use and can be easily tripped by watching too many videos or asking Siri too many questions over wireless devices, they say.

Carriers, they say, need to do a better job explaining how much data is being used by new services.

“It’s a black box,” said Art Brodsky, spokesman for consumer group Public Knowledge. ”And it means consumers can have access to great new services but also end up paying more for using them.”