I don’t dare install OS X El Capitan* out in the field high in the mountains at 10,600' in a snowstorm, but I was curious whether my “unlimited” iPhone (which I have kept for years, paying extra for the grandfathered unlimited plan)—well, I was wondering if AT&T would throttle the speed after some amount of bandwidth utilization, thus making a fraudulent mockery of “unlimited”.
At the 4.5GB mark, the download speed ranged from 1.4 to 2.1 MB/sec, which is 13-16 megabits per second—faster than the speed of many home internet connections. Not bad. If that speed continues, it will be satisfying.
Update: at around the 4.8GB mark, average speed is dropping to about 1.1 - 1.5MB/sec. Given the storm, it’s hard to state with certainty that AT&T is throttling the speed, or something else. But it sure looks like dishonest/fraudulent “unlimited”, given the consistent performance for an hour or so. After paying for years and hardly using any bandwidth, that sure is a lousy thing to do (if true but it's now very consistently down to about 1.2 MB/sec as I write this). When I paid for unlimited (for 3-4 years now), I took AT&T at their word. Maybe this is just normal variability, but it seems to have steadily been declining in speed, and I have line-of-sight to the cell tower.
Update 2: perhaps the cynicism was unwarranted: speed recovered to ~2MB/sec towards the 6GB mark, and the entire download succeeded.
* Given Apple’s shoddy quality control, I cannot take the chance on losing functionality until I return home from my trip.