Sprint Nextel (NYSE: S) reported earnings last week, and one of the big points of the conference call was what CEO Dan Hesse called a "two-and-a-half-year companywide obsession" with customer satisfaction.

Hesse says it has paid off with more improvements than any other carrier in various customer satisfaction scores, as well as "port-in" statistics, which measure how many customers switch to Sprint from a rival carrier like AT&T (NYSE: T) or Verizon (NYSE: VZ). That metric is up 84% year over year.

Despite a recent survey showing that Apple (Nasdaq: AAPL) iPhone users are pretty satisfied with AT&T, it doesn't seem non-iPhone users share the same contentment. All AT&T customers would like to see their carrier become as obsessed with customer satisfaction as Sprint.

Fool analyst Rex Moore likes seeing a strong focus on the customer. It makes sense; satisfied customers will produce less churn, are more likely to renew, and will give you good word-of-mouth advertising.

The bottom line: This is just one aspect of evaluating Sprint as an investment, but laser-like focus on customer satisfaction can create a somewhat hidden upside.

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Fool analyst Rex Moore salutes National Salute Week. He owns no companies mentioned in this article. Sprint Nextel is a Motley Fool Inside Value selection. Apple is a Motley Fool Stock Advisor recommendation. Try any of our Foolish newsletters today, free for 30 days. The Motley Fool has a disclosure policy.