Hello, Data Hog! Verizon's About to Slow You Down (and Compress All Your Web Content)

A big perk of Verizon over AT&T—besides phone calls—is unlimited smartphone data versus AT&T's 2GB cap. But! If you're pulling too much data, Verizon will slow your roll. This is how Verizon's getting ready for the iPhone flood.

Specifically, a PDF on Verizon's site spotted by Boy Genius says:

If you use an extraordinary amount of data and fall within the top 5% of Verizon Wireless data users we may reduce your data throughput speeds periodically for the remainder of your then current and immediately following billing cycle to ensure high quality network performance for other users at locations and times of peak demand.

They won't stop you from pulling down 10GB a month over your smartphone. But they will make a bit harder to pull that much data down in the first place. The question is, how much data puts you in the top 5 percent? One study from July would put people using more than 2GB of data on Verizon's network in the top 5 percent of data users. (Which is, notably, about the same as AT&T's data cap.)

The other thing Verizon's doing to manage data is "implementing optimization and transcoding technologies in our network to transmit data files in a more efficient manner," doing things like "include caching less data, using less capacity, and sizing the video more appropriately for the device." Sounds fine! Except:

While we invest much effort to avoid changing text, image, and video files in the compression process and while any change to the file is likely to be indiscernible, the optimization process may minimally impact the appearance of the file as displayed on your device. For a further, more detailed explanation of these techniques, please visit www.verizonwireless.com/vzwoptimization.

Right now, that link's dead, so we'll have to wait and see what this is going to mean in detail. Update: Link's live. It explains further:

All HTTP (Port 80, i.e., World Wide Web) traffic is directed to the optimization process. The direction of traffic to the optimization process is established when the user starts an HTTP data session before any requests for content from a specific web site have been made. Accordingly, content files are not selected for optimization based on the nature of the web content itself or the source or provider of the web content file. All web content files delivered over Port 80, regardless of source, are directed to the optimization process. The system thus captures all Verizon Wireless branded web content delivered from its web servers, and treats such content in the same way as content of the same type requested from non-Verizon Wireless sites on the Internet.

The process incorporates several optimization techniques that depend upon the specific type of content file. Specifically, text files are compressed without any loss of information ("lossless") and cached for subsequent end user requests. Image files (PNG, JPEG, GIF formats, for example) are streamlined to remove colors or other data bits that would not be visible to the human eye, or to end users on a mobile device with limited display resolutions, thereby decreasing the size of the file, and also cached. The output image file reflects "lossy" optimization because some data bits from the original file are lost in the optimization process. ...

Optimization transcodes video files from their source codecs to a more efficient codec, H.264. If the requesting device cannot decode an H.264 file, the file is delivered in the input codec. Also, if the input file codec is H.264, there will be little or no effect on the file from the processes described below.

Innnnnteresting.

It's an interesting set of tradeoffs: With Verizon, you get unlimited data and better phone calls, but you might get slowed down and there's a chance some files will look weird. With AT&T, if you can get a connection, it's going to be faster, but you're going to pay for every byte. Sprint's unlimited plans are looking pretty good right about now! (Cue question: When are they getting the iPhone???) [VZW, VZW via BGR]

P.S. Any Verizon network engineers wanna talk about the new web compression stuff? We'll keep it anonymouse-y! Email me!