In its first survey of iPhone owners since Apple (AAPL) began selling a version of the iPhone 4 through Verizon (VZ), ChangeWave Research found that the overall satisfaction of Verizon iPhone owners was “virtually indistinguishable” from that of those using the AT&T (T) version — despite the fact that AT&T continues to drop calls more than any other major U.S. carrier.

82% of Verizon customers pronounced themselves “very satisfied” with their iPhones versus 80% of AT&T owners, while 16% and 18%, respectively, said they were “somewhat satisfied.”

Meanwhile, both companies seem to be making progress on the dropped-call front. The frequency of dropped calls over the past 90 days among AT&T respondents dropped from a high of 6% in September to 4.6% in March. Among all Verizon customers, the frequency was 1.4%, the lowest ever recorded in a ChangeWave survey. For Verizon iPhone owners, however, the rate was slightly higher: 1.8%

Below: The rest of ChangeWave’s latest charts.

ChangeWave’s survey of 4,068 consumers was completed on March 28. A summary of its findings is available here. The complete report costs $1,500.