Alltel customers get the best mobile call quality in the United States, according to a J.D. Power and Associates semi-annual study.

Alltel led in the Southeast and Western regions, and tied with T-Mobile in the Southwest. Verizon Wireless ran a close second, winning in the Northeast and Mid-Atlantic regions, the study found.

Other notable results included Verizon’s win in the Mid-Atlantic, which was its seventh consecutive award in the region, and U.S. Cellular picked up its fifth consecutive win in the North-Central region.

Also in the study, the researchers found that carriers using CDMA networks fared well because fewer towers are needed, causing fewer opportunities for dropped connections, as did carriers running 3G networks because of the greater bandwidth available.

The research firm studied 24,570 users and inquired about typical mobile call problems such as dropped calls, static/interference, failed connections, voice distortion, echo, voice mail notification and text message notification. The rate of such problems has been declining for several years, but now seems to be leveling off.

“This is the first [study] in a year …that we haven’t seen either a directional or significant decline in problems,” explained Kirk Parsons, senior director of wireless services. But long-term meaning is difficult to extract from that result. “If we see this again in another six months from now, we could maybe draw some conclusions that way.  For right now it’s hard to tell,” he said.

AT&T and Sprint Nextel finished below the national average in all six regions.  Both companies had three last-place finishes.

“Everyone has their problems. It depends on short-term issues, so that can be fixed,” Parsons said.

The study is in its sixth year.