Have you been a loyal iPhone or iPhone 3G customer since day one on AT&T? Or maybe you've stuck it out on Verizon for like, ever. If you haven't changed your contract, you probably have an "unlimited" data plan. Until recently that meant, in theory and in practice, you could stream, download and upload all the data you wanted from your phone, and pay one flat fee for all those megabytes or gigabytes.
Last year, AT&T and Verizon moved to tiers of data--you pay, say, $25 for 2GB, and more for anything over that--and added a new provision for "unlimited" data customers: If you were in the top five percent of data users, they'd slow your phone's internet down. Way, way down, in some cases. (Google "AT&T throttling unusable.") But what is the top five percent of data users? Who is a five percenter? We got vague guidelines like this one from Verizon: "If you’re on an unlimited data plan, have a 3G device and are using more than 2 GB of data in a month, you’re in the top 5% of data users..." This past week, AT&T "clarified" what "unlimited" now meant for 17 million subscribers: 3GB a month on 3G device, or 5GB a month on a 4G device. (Why someone with a slower phone is allowed to download less data, I cannot tell you, but Verizon has a similar policy in place.) After crossing those lines your data speeds hit a bump.
Here's the kicker: AT&T won't tell anybody how much it'll slow you down after the 3GB/5GB limit. It refuses to comment on the record what kind of speeds throttled users should expect. More to the point, maybe, it won't even comment on the record as to why it won't tell anyone what kind of speeds they should expect. That's some Soviet-style silence.
Verizon doesn't publish "optimized" speeds, either, but a spokesperson at least explains that's "because the speed you are dropped to depends on how many users are on the same site at that time and what data applications are being used on that site at that time."
Anecdotally, before AT&T's Great Clarification, the top throttled speed seemed to be an nigh-unusable 64kbps, but now it appears to be far less prohibitive 256kbps. Verizon's may well be slower, but--and this is a big but--it only slows down unlimited users who've crossed the line when they're connected to a congested tower. In other words, Verizon actually manages the network based on demand; AT&T just punishes you for the entire billing cycle.
Network management isn't an inherently bad thing. Bandwidth is a limited resource, as Dan Frommer is wont to remind us, and it's true that AT&T (and Verizon) always reserved the right to manage the network. That's fine. But the carriers should stick to the spirit of their promises to customers and network management should be reasonable--not both secretive and punitive, which is how AT&T's policy comes across. Unfortunately, this industry still seems much better at keeping secrets than promises.