According to an extensive comparative study of iPhone 4S (s aapl) performance across all three major U.S. carriers, AT&T(s t) offers by far the best data performance on paper, and also performs nearly as good, or better, than both Sprint and Verizon in terms of call quality and reliability.
One of the chief complaints against AT&T for as long as it has had the iPhone has been its tendency to drop calls with alarming frequency. The new study by Metrico, a wireless performance measurement company, indicates that AT&T’s call failure rate of 2.8 percent was actually better than Sprint’s(s s) (3.7 percent), though it was worse than Verizon’s(s vz) (2.1 percent). Metrico tested call performance in five major unnamed U.S. cities it says are “representative” of the overall country, and used more than 6,000 voice calls to get its results.
The iPhone 4S performed poorly in general in terms of call failure rates when compared to the competition in terms of Android (s goog) and BlackBerry (s rimm) devices, which could be attributable to the fact that it packs both CDMA and GSM support into a device originally designed to work with just one or the other, but did much better than average in terms of data performance.
Data and web browsing was where AT&T really shined. It managed more than double the average download speeds of both Sprint and Verizon, with 3210 Kbps vs. 1071 Kbps for Verizon and 581 Kbps for Sprint. Sprint’s low score echoes user complaints that prompted the network to tell reporters it’s “taking the reports of problems […] seriously.” It’s no surprise that AT&T dominates when it comes to data scores, since it’s the only iPhone carrier to offer HSPA+ speeds thanks to its upgraded GSM network, which the 4S supports.
Despite the difference on paper, Metrico rated all three major U.S. iPhone carriers very highly in terms of their ability to deliver full data reliably to customer devices. Still, comparative web page load times might give those still deciding between carriers something to think about: AT&T devices loaded pages in 1.29 seconds on average, compared to 2.6 seconds on Verizon and a relatively sluggish 6.44 seconds on Sprint.
Sprint took the lead when it came to voice quality when speaking, however, though AT&T wasn’t far behind. Out of a possible maximum score of five, Sprint ranked 3.95 when speaking, while AT&T was next at 3.85 and Verizon came in third at 3.5. In terms of voice quality when listening, AT&T was highest with 3.82, with Sprint second at 3.72 and Verizon last at 3.55. Metrico uses an algorithm to score call quality objectively.
Metrico stresses that the study isn’t meant to delineate a winner among the three iPhone 4S carriers, and suggests that users will have a different preference based on needs. But in a smartphone market where data and data services are increasingly replacing voice calls both in terms of usage trends among users and revenue drivers for carriers, AT&T’s data performance could actually make it the best among the three for the average smartphone user. That might not be the case for long, however, since a future iPhone could well include LTE support, which is an area where AT&T lags behind Verizon considerably.