By Tarmo Virki, European Technology Correspondent
(Reuters) - Apple's new iPhone 4S consumes on average twice as much data as the previous iPhone model and even more than iPad tablets due to increasing use of online services like the virtual personal assistant Siri, an industry study showed.
When Apple rolled out the iPhone 4S in October, its small improvements disappointed many analysts and reviewers, but consumer demand for the device has been strong, and buyers have extensively used their devices.
IPhone 4S users transfer on average three times more data than users of the older iPhone 3G model which was used as the benchmark in a study by telecom network technology firm Arieso.
Data usage of the previous model, the iPhone 4, was only 1.6 times higher than the iPhone 3G, while iPad2 tablets consumed 2.5 times more data than the iPhone 3G, the study showed.
Today's generation of smartphones is placing increasing demands on available carrier bandwidth as applications become slicker and average personal usage of videos intensifies.
That sharp rise in data consumption puts more pressure on wireless operators to speed up capacity investments, as they are struggling already with clogged telecom networks to keep up with growing demand for data services on the go.
A smartphone's consumption of data depends upon what the user asks it to do.
The iPhone 4S is perceived by some as a data hog because of Siri, a well-reviewed virtual personal-assistant and search app. It is integrated into the iPhone 4S and responds to voice commands.
"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.
He said as tablets use smartphone-like user interfaces and software platforms, their data usage was similar to top-end smartphones.
"A tablet still looks like a big smartphone," he said.
Mobile data usage has skyrocketed since the introduction of Apple's original iPhone in 2007, with usage of data networks seen roughly doubling each year. Emerging mobile cloud services such as Siri are expected to further boost growth.
Wireless operators are keen on raising revenue from Internet browsing and the social networking boom as revenue from traditional voice calls declines, but they are facing increasingly congested networks.
Fearful of losing customers, only a few operators have publicly admitted to the problem of keeping pace with data traffic, but the majority are experiencing difficulties.
"There is no silver bullet," Flanagan said, adding that the introduction of new, more efficient LTE networks will help. But he said operators should also identify heavy users of data and distribute small cellsites to them to offload traffic from mobile networks.
New, so-called small cell technologies enable operators to use tiny, almost personal base stations which cost around $100 to remove mobile data traffic from the big base stations which serve hundreds or thousands of clients around them.
Telecoms gear makers Ericsson, Nokia Siemens Networks and Alcatel-Lucent -- which have had to battle aggressive pricing by Asian rivals -- hope rising data traffic will lead to new orders.
(Reporting By Tarmo Virki in Helsinki, editing by Matthew Lewis)