The reliability of a wireless network depends largely on what you’re doing and what type of device you’re doing it on, according to study published today by J.D. Power and Associates.

Now in its ninth year, the semiannual Wireless Network Quality Performance Study—Volume 2, has been expanded in 2011 to collect evaluations from wireless customers’ most recent usage activities in three areas that impact the network performance: calling, messaging and data.

The study bases overall network performance on 10 problem areas that impact the customer experience: dropped calls; calls not connected; audio issues; failed/late voicemails; lost calls; text transmission failures; late text message notifications; Web connection errors; email connection errors; and slow downloads. Network performance issues were measured as problems per 100 network connections, where a lower score reflects fewer problems and better network performance. Carrier performance is examined in six regions: Northeast; Mid-Atlantic; Southeast; North Central; Southwest; and West.

The study found that there were more reported problems among wireless customers while placing calls, compared with messaging and data-related activities. Overall, problems associated with calling, such as dropped calls, initial disconnects and audio issues, average 18 out of 100. This compares with a reported 16 out of 100 average for data-related issues, such as Web and email connection errors and excessively slow downloads. An even lower PP100 average is reported for messaging problems (5 out of 100), such as transmission failures and late text messages.

“Based on the varying degree of consistency with overall network performance, it’s critical that wireless carriers continue to invest in improving both the voice quality and data connection-related issues that customers continue to experience,” said Kirk Parsons, senior director of wireless services at J.D. Power and Associates.

According to Parsons, there is a financial impact in providing a high-performing network, as spending increases by an average of $10 per customer among those who have switched from a previous carrier to obtain a better network/coverage, compared with those who leave for other reasons.

For a 14th consecutive reporting period, Verizon Wireless ranked highest in the Northeast region. The study found that Verizon Wireless achieves fewer customer-reported problems with dropped calls, initial connections, transmission failures and late text messages, compared with the regional averages. Verizon Wireless also ranks highest in the Mid-Atlantic, Southeast, Southwest and West regions.

In the North Central region, U.S. Cellular ranked highest for a 12th consecutive reporting period. Compared with the regional average, U.S. Cellular has fewer customer-reported problems with dropped calls, failed initial connections, audio problems, failed voice mails and lost calls.

The study also found that fewer calls are being made or received. On average, wireless customers use 450 minutes per month, a decline of 77 minutes from 527 in 2009. Customers are using their devices more often for text messaging, according to the study, which found that wireless customers sent/received an average of 39 text messages during an average two-day period. During the course of a month, this equals more than 500 incoming/outgoing text messages.

On average, smartphone customers continue to experience more problems than do traditional handset customers, 14 out of 100 vs. 12 out 100, respectively.

The study is based on responses from 22,110 wireless customers. The study was fielded between January and June 2011.