The iPhone 4S's Siri voice assistant has led to a massive increase in mobile data consumption, according to a study from telecom network technology firm Arieso. Aresio's research shows that owners of the iPhone 4S are using twice as much data as owners of the iPhone 4, and three times as much data as owners of the iPhone 3G.

By way of comparison, the owners of the iPhone 4 use 1.6 times as much data as owners of the iPhone 3G, and owners of the iPad 2 use about 2.5 times more data than the iPhone 3G.

Smartphone users have become a data-hungry lot.

This is evidenced in moves made in 2011 by top-tier carriers such as AT&T, T-Mobile USA, and Verizon Wireless, which all adopted tiered data plans and nixed their unlimited data offerings. The idea was to curb mobile broadband usage on 3G networks as they roll out their 4G networks. Apple found a way to challenge those moves with the iPhone 4S.

[Check out 5 Ways The Smartphone Market Evolved In 2011.]

The iPhone 4S's Siri voice assistant is being blamed and here's why. Users speak commands or requests into the iPhone 4S and Siri takes action. In order to make this happen, Siri records the spoken commands and then sends the audio file over the network to Apple's servers. Once it reaches Apple's servers, the audio file is translated into text, which is then analyzed by Apple's servers for meaning and context. Once the transcribed audio is understood, Apple's servers fire a message back to Siri--over the network again--on the iPhone 4S, with directions on what to do. Sometimes that task means returning search results, opening Web pages, making phone calls, or sending text messages. Everything about Siri requires a network connection.

"I use the iPhone 4 myself and when I first heard of the iPhone 4S features I was not compelled to rush out and get one. However, the data usage numbers I am seeing make me wonder what I am missing," said Arieso's chief technology officer, Michael Flanagan.

Beyond Siri, one of the biggest threats to mobile broadband networks is video. All modern smartphones and tablets are capable of playing streamed video content, which is delivered over the network. For example, Google's YouTube service is available to most smartphones and tablets. Users aren't just streaming video content, however. They're creating it, in high definition, and uploading it to the Internet. An average one-minute high-definition video can be as much as 100 MB. That's a lot of data to push through mobile networks at one time.

Carriers are facing a catch 22 with mobile data. They offer it at a premium to drive profits, especially since revenue from voice and messaging services is on the decline. But the cost to build and maintain the networks against the rising tide of data usage is a heavy burden to bear.

"There's no silver bullet" to fix the problem, said Arieso's Flanagan, though he suggests that network operators should identify the largest consumers of mobile data and give them in-home base stations, called femtocells.

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