A new study published by ChangeWave Research indicates that iPhone 4 users are more than twice as likely to experience dropped calls on AT&T's network than Verizon's. According to data submitted by 4,068 iPhone 4 owners over the last 90 days, Apple's handset has a 4.8% chance of dropping a call on AT&T's network versus 1.8% on Verizon's.

That shouldn't come as a total shock as it's in line with ChangeWave's industry-wide dropped call rates of 4.6% for AT&T subscribers and 1.4% for Verizon customers – and let's face it, AT&T has long been chastised for having spottier coverage. In December, Consumer Reports rated AT&T as the worst carrier in the US, while Verizon was the second best.

Despite experiencing more dropped calls, 80% of iPhone 4 users on AT&T are very satisfied, while 18% are somewhat satisfied. That compares with 82% and 16% for Verizon (both add up to 98% satisfied). Although existing customers might be happy, 46% of those who plan to buy an iPhone 4 in the future say they'll shop with Verizon versus 27% for AT&T.

T-Mobile ranked second in ChangeWave's overall industry figures with 2.3% of calls dropped in the past 90 days, while Sprint placed third with 2.7%. It should be interesting to see if these numbers change in the next year as Verizon's network is bombarded by iPhone users and AT&T gains control of T-Mobile's towers – assuming their deal is approved.