Study: AT&T, not Apple, is to blame for dropped iPhone 4 calls

When AT&T was the sole service provider for the iPhone, both the company and the device garnered criticism for a purportedly high rate of dropped calls. A study by research company ChangeWave suggests that AT&T deserves the lion's share of the blame.

The company has the highest rate of dropped calls among the top four mobile providers, whereas new iPhone carrier Verizon has the lowest rate of dropped calls. These findings, based on responses from 4,068 customers of AT&T, T-Mobile, Sprint/Nextel, and Verizon, may shed some light on why AT&T is eager to sink its claws into T-Mobile. Perhaps the extra infrastructure would give AT&T's service levels a needed boost or at least average out the carrier's overall dropped call rate on paper. According to the study, AT&T users suffered a 4.6 percent dropped-call rate in a 90-day period. On the other end of the spectrum, Verizon subscribers registered only a 1.4 percent dropped-call rate during the same time period. T-Mobile's dropped-call rate was 2.3 percent, and Sprint/Nextel's was 2.7 percent. ChangeWave also compared historical dropped-call rates over 90-day periods between Verizon and AT&T between September 2008 and March 2011. Invariably, Verizon had fewer dropped calls and in fact saw that rate drop from 2.7 percent in September '08 to 1.4 percent in March of this year. AT&T, meanwhile, steadily rose from 3.3 percent in March 2009 to a spike of 6 percent last September before gradually declining to its current rate of 4.6 percent.