“Voice is the ultimate human interface,” Arieso Chief Technology Officer Michael Flanagan said in an interview in London. “As you lower the barriers,” consumers will use their smartphones’ functions even more often, he said. Arieso, based in Atlanta, advises clients such as Vodafone Group Plc (VOD), Telefonica SA (TEF) and Nokia Siemens Networks Oy on how to manage wireless networks.

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. Arieso said it measured more than 1 million subscribers across a single European network in both urban and rural areas, without identifying the operator.

The strain of data-intensive devices may place additional pressure on mobile operators as they build out faster networks. Verizon Wireless, the largest U.S. carrier, said this week the number of iPhones it sold doubled to 4.2 million in the fourth quarter.