Owners of Apple's iPhone 4 on the AT&T network are more than twice as likely to report dropped calls than Verizon customers, according to a new survey by the ChangeWave research group (http://www.changewave.com).

A new ChangeWave survey of 4,068 consumers has taken a close up look at key comparisons between Verizon iPhone 4 owners and AT&T iPhone 4 owners – including customer satisfaction and dropped call rates.

The ChangeWave survey, completed March 28, was conducted several weeks after Verizon began offering the iPhone 4. Among other things, the results provide insight into how owners believe the AT&T and Verizon iPhones stack up against each other in a couple of key areas.

In terms of overall satisfaction the two iPhones are virtually indistinguishable. A look at the Very Satisfied ratings for each shows 82% of Verizon iPhone 4 customers saying they're Very Satisfied versus 80% of AT&T iPhone 4 customers.

For the past few years ChangeWave has been tracking overall dropped call rates among the major wireless service providers in its consumer surveys. In the current survey, Verizon continues to maintain the best overall rating in the industry, with their customers reporting on average only 1.4% of calls dropped over the past 90 days. T-Mobile (2.3%) comes in second, followed by Sprint/Nextel (2.7%).
AT&T ranks last among the four major providers in the current survey. Its customers report an average of 4.6% of calls dropped over the past 90 days.

AT&T has trailed Verizon in terms of overall dropped call rates since ChangeWave first began surveying on the subject back in September 2008. However, in our previous survey in December 2010 the research group noted that AT&T had registered a significant improvement on this measure. And in the current survey of 1,264 AT&T subscribers, their overall dropped call rate has improved once again, if only slightly (from 4.7% to 4.6%).

At the same time, the overall dropped call rate among the 1,283 Verizon subscribers surveyed is now at its lowest level ever recorded in a ChangeWave survey (1.4%).

Similar to the historical patterns in our overall industry findings -- Verizon iPhone 4 owners currently report a lower dropped call rate than their AT&T iPhone 4 counterparts.

In sum, while the survey finds overall customer satisfaction ratings are virtually indistinguishable between Verizon iPhone 4 owners and AT&T iPhone 4 owners, there are apparent differences in the relative percentage of reported dropped calls -- where in the current survey Verizon is outperforming its industry rival.

ChangeWave notes, however, that Verizon is still in the early stages of its iPhone 4 offering to consumers. It remains to be seen how well the Verizon network performs as the number of Verizon iPhone 4 owners ramps up and inevitably puts more pressure on their system, says the research group.

And in a sign of the magnitude of the ramp-up Verizon is facing, 46% of those who plan on buying an iPhone 4 in the future say they'll use Verizon as their service provider compared with 27% for AT&T.