Editor's note: Amy Gahran writes about mobile tech for CNN.com. She is a San Francisco Bay Area writer and media consultant whose blog, Contentious.com, explores how people communicate in the online age.
(CNN) -- If you're in the market for a new cell phone, you'll probably have a better buying experience if you visit the carrier's store to shop and make the purchase, rather than buying online or over the phone, a new survey says.
J.D. Power and Associates recently surveyed about 11,000 U.S. wireless customers who purchased a cell phone within the last six months (9,200 customers with full-service wireless contracts, and 1,800 noncontract mobile users). They rated customer satisfaction on a 1,000-point scale, according to six criteria.
What's the least satisfying way to buy a cell phone? According to J.D. Powers: "Satisfaction is lowest among customers who most recently conducted a Web sales transaction (738 on a 1,000-point scale, on average), compared with retail (walk-in) and telephone channels (753 and 752, respectively).
"Customers who purchased through the Web channel, where finding information quickly is more challenging, tend to rate their experience lower based on the general lack of personal assistance, compared with either in-person or over the phone."
Also, you may not get the best deal (in terms of the cost of the phone and plan) when buying over the phone. The survey found that "satisfaction with cost of service among purchases occurring over the phone averages 626, compared with 653 and 652 when purchases occur online and in stores, respectively."
That said, survey participants reported being significantly more satisfied when they called the carrier to change their plan, compared with going online to change their plan.
Contract wireless customers gave the highest overall buying-experience marks to Sprint and T-Mobile -- both scored 755. AT&T scored 744, the worst ranking from contract customers.
J.D. Powers noted that Sprint excels in its online sales experience, as well as in its variety of plan offerings and promotions, and cost of service. Overall, T-Mobile offered the most affordable cost of service.
A broader range of overall satisfaction marks was given for buying phones from noncontract carriers. Boost Mobile led the pack with an overall customer satisfaction score of 766 (surpassing all contract carrier ratings). Tracfone trailed at 708. The average score among noncontract carriers was 740.
According to J.D. Powers, "Boost Mobile performs particularly well in phone sales representative, offerings and promotions, and cost of service."
How are people buying phones? The survey indicates that roughly 60% of both contract and noncontract mobile customers most recently purchased a phone while visiting a retail store. This could be a carrier's retail store, a third-party retailer such as Apple or Best Buy, or even a supermarket or drugstore (where many noncontract phones are sold).
The survey noted: "Satisfaction with the overall purchase experience among other retailers, such as Apple, Best Buy, Costco, RadioShack and Wal-Mart, averaged 740 -- 18 points lower than among stores owned by full-service wireless carriers."
The opinions expressed in this post are solely those of Amy Gahran.