AT&T has the nation's fastest data network, but when it comes to its voice network, the picture isn't quite that pretty.  Verizon has long touted its superior voice network over AT&T, so this year AT&T tried to do something about it increasing its infrastructure investment by $2B USD over last year's investment.  The new investment was geared at shoring up trouble spots in cities, in particular.

Surprisingly, a study [PDF] by ChangeWave Research surveying 4,040 smartphone subscribers claims that AT&T's voice network metrics are actually getting worse.  From March 2009 to March 2010, the study claims AT&T dropped calls rose from 3.3 percent to 4.5 percent.  Competitor Verizon, meanwhile, saw its dropped call rates dip from 1.8 percent to 1.5 percent over the same time period.

The next highest dropped call rate after AT&T was T-Mobile with a 2.8 percent dropped call rate in March 2010.

Aside from dropped calls, the survey also claims that AT&T subscribers are quite unsatisfied with their voice network experience.  AT&T was tied with T-Mobile in March 2010 for the lowest satisfaction rate, with 23 percent of subscribers reporting satisfaction.  Verizon, by contrast, had a 49.9 percent satisfaction rate.

The study comments, "AT&T was clearly the worst in the March survey, tacking on yet another increase over the latest ChangeWave research survey.  Furthermore, a closer look at the trends show an increasing number of dropped calls among AT&T customers surveyed, and a steadily decreasing number of dropped calls for Verizon customers."

AT&T carries more smartphones than any other network in the U.S., currently.  It is the exclusive carrier of Apple's popular iPhone which that currently holds about 25 percent of the market (after only RIM's many BlackBerry handsets, which collectively hold 40 percent of the market).  Despite owning exclusive U.S. distribution rights to what many view as the world's hottest smart phone, AT&T has had some trouble dealing with the increased network stress that smartphones and more subscribers bring.

As part of its efforts to improve call quality, it has reportedly been hard at work with partner Apple to improve the way the iPhone interfaces with the AT&T network.  Tweaks to the iPhone firmware reportedly increased the data network speed by 84 percent between December and April, and also attempted to improve the voice network experience.

We've been in contact with AT&T spokespeople -- they refute the study's conclusions and are working to get us some independent numbers that they feel show the true picture.  We will update as soon as we get those.

We encourage any customer who is having an issue to call us so we can understand what's going on.  We value feedback of all kinds.  We continue to focus on network improvements and continue to offeri the best device lineup,  A great measure of satisfaction is customer churn, which continues to go down including in our most recent quarterly earnings, where it was a best-ever 1.07 percent for postpaid customers.

The opinions compiled in this survey are dramatically at odds with actual quantitative results derived from millions of calls made during extensive drive-testing of the AT&T mobile broadband network by a highly respected outside firm.  Those results, from GWS, show that, on a national basis, AT&T is within just two-tenths of a percent of the industry leader in wireless call retainability.  That's a difference of just two calls in a thousand, a virtual dead-heat.  In fact, the statistically valid drive tests shows the AT&T network continues to deliver the nation's fastest 3G network and near best-in-class call retainability nationwide. In those recent drive tests, AT&T's network dropped only 1.44 percent of calls nationwide, within two-tenths of 1 percent of the industry leader and a difference of less than two calls out of 1,000."