Earlier today,in San Francisco, New York, Los Angeles, and eight other cities.
The move comes almost a month after LTE wason compatible smartphones in San Francisco and elsewhere, before AT&T had begun supporting it in full. Trials like that are not unusual for carriers.
To quickly test the speeds, I grabbed up the HTC Vivid--one of three compatible LTE phones, alongside the Samsung Galaxy II Skyrocket and the --and ran Speedtest.net, a free app we often use to measure speed diagnostics.
Speeds were much faster on the Vivid, which often tripped and stuttered duringwhen LTE was still in trial, when it wasn't peaking at download speeds of 19Mbps. This time around, download speeds ranged from 17Mbps to 25Mbps.
Tested from one location right now (the CNET office), this certainly isn't the final word in San Francisco's 4G LTE experience for AT&T. However, speeds do continue to look promising, and we'll continue to keep watch.
Of course, many factors affect network performance, including the particulars of the hardware itself and the volume of data demands at a given time, known as network load. The real test is how AT&T's 4G LTE network holds steady, or falters, further down the line, as more users snatch up the carrier's LTE-ready phones.