Apple's voice recognition software Siri has prompted users of the iPhone 4S to use almost twice as much data as compared with iPhone 4, according to a report published by network management software vendor Arieso.

The iPhone 4S takes data consumption to new levels, says Arieso's report. Apple's iPhone has put some operator networks under immense pressure since the first version arrived, as users download more data than their networks can handle. The new generation of smartphones is placing increasing demands on available carrier bandwidth.

The main reason for the growing data volume is the addition of Siri. Apple brought in Siri, dubbed a virtual personal assistant, in its latest iPhone update in October. With a few spoken words, the artificial-intelligence feature helps iPhone users schedule appointments, write text messages and check the local weather.

As a result of the fear of losing customers not many operators have come forward to admit to the problem of keeping pace with data traffic. But the fact is that the wireless operators are already struggling to speed up capacity investments, as they are faced with congested telecom networks. Ever since the introduction of Apple’s original iPhone in 2007, data usage by mobile devices has increased rapidly, with usage of data networks almost doubling each year. In addition to this, the emerging mobile cloud services such as Siri are expected to further boost growth.