U.S. mobile operators that offer Apple’s iPhone uniformly report hits to their profit margins due to the device, but data from the Yankee Group (http://yankeegroup.com) reveals a significant silver lining.

According to the report “iPhone Conundrum: Profit Drag or Halo Effect?” carrying the iPhone immensely improves customers’ overall impression of the operator brand, especially among Apple users. Other OS or device brands — such as Android or Samsung — fail to show a similar impact.

“But it also brings subscribers in droves as well as significant improvements in how those users view operator brands,” says Rich Karpinski, Yankee Group senior analyst and author of the report. “ith the latest iPad focused strongly on 4G, and an LTE iPhone likely to appear later this year, U.S. operators that find ways to successfully manage the ‘i-challenge’ win.”

The report reveals:

° AT&T boasts the largest iPhone halo effect. Among Apple users, AT&T ranks No. 7 out of 20 top mobile brands. Among all users, it ranks No. 14.

° Sprint registers immediate gains. While the impact on AT&T’s brand grew over time, Sprint’s impression scores nearly doubled just in the first quarter selling the device.

° Verizon sees little brand impact. Verizon does not see a corresponding boost in its brand among core Apple users. Overall, customers seem to value Verizon’s brand highly, regardless of the device they use.