The incidence of data quality problems has risen for the first time in more than four years, according to the newly released J.D. Power 2014 U.S. Wireless Network Quality Study—Volume 2.

The research firm attributed the higher incidences to the increased use of tablets and other mobile broadband devices, which generate different usage patterns and network quality expectations compared to smartphone and feature phone users, the company said.

“While customers may be leveraging the same network across a multitude of devices – including smartphones, tablets and mobile broadband devices – their experience can be different given the variety of locations in which they are used and the different activities performed on each,” said Kirk Parsons, senior director and practice leader of telecommunications at J.D. Power.

To that point, Verizon Wireless earned the highest rankings in five U.S. regions: the northeast, southeast, north central, southwest and west. Its call, messaging and data quality took top honors in those areas.

But AT&T got top honors in the Mid-Atlantic region, particularly in terms of data quality.

T-Mobile ranked about average in most regions, although it got a “better than average” in the west, southwest and the northeast. Meantime, Sprint sat at the bottom in every region.

J.D. Power’s semiannual study is in its 12^th year. Researchers based their findings on responses from 26,205 wireless customers between January and June of this year.