Since the release of the Verizon iPhone 4, AT&T and Verizon have been in a very public battle over whose call quality is better. A recent survey conducted by research company ChangeWave suggests Verizon may offer better service.

According to the survey, which relied on customers self-reporting, 4.6% of calls made on AT&T's network were dropped, compared to 1.4% of subscribers to Verizon Wireless, which ranked last in the number of dropped calls.

Rates for dropped calls are slightly higher for iPhone users. According to users, 1.8% percent of Verizon iPhone 4 calls were dropped, a significant number in comparison to the 4.8% percent reported by AT&T subscribers.

AT&T was roundly criticized when the company first rolled out the iPhone 4, with numerous complaints of dropped calls and problems when their network was overwhelmed with heavy data usage. Since then, AT&T has said network quality has improved dramatically and in its advertising it regularly touts its network's speed.

Overall satisfaction rates for Verizon and AT&T customers were almost identical. 82% of Verizon users and 80% of AT&T owners said that they were 'very satisfied' with their phones.

As, ChangeWave reports, however, Verizon is still fairly new to the iPhone business. 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, the study said.