Â鶹ÒùÔº

(AP) -- Improvements in customer satisfaction at Sprint Nextel Corp. and AT&T Inc. have narrowed differences among the Big 4 wireless carriers to the point that they're basically even in terms of pleasing their subscribers, according to a study released Tuesday.

The American Customer Satisfaction Index puts Sprint, AT&T, T-Mobile USA and Verizon Wireless within two points of each other on a 100-point scale of customer satisfaction.

That's the smallest spread since the survey started looking at all four companies in 2005. It's also within the margin of error at plus or minus three points.

Last year, AT&T clearly trailed the pack, while Sprint and Verizon led. That was a surprising development for Sprint, which was last as recently as four years ago. Sprint CEO Dan Hesse has made improvement in customer service central to his tenure.

AT&T recovered this year, with a three-point increase to 69. It shares that score with T-Mobile USA, the No. 4 carrier by size. Verizon and Sprint are at 70 and 71, respectively.

The survey was developed by the University of Michigan, but is now run by a private company, ACSI LLC. It surveyed about 6,000 households in the first quarter for the annual report.

For the phone companies, the satisfaction index has a limited relevance to actual customer loyalty, which the companies report quarterly. For instance, T-Mobile customers are far more likely to leave the carrier than AT&T's are, even though they have the same score.

T-Mobile is the only company among the Big 4 that doesn't sell the iPhone. That probably matters to customers. The ACSI for the first time published a score for Apple Inc. as a phone manufacturer. At 83 points, it handily outranks other manufacturers measured, including Samsung Electronics Co., HTC Corp. and Motorola Mobility Holdings Inc.