Last month we were the first to report that AT&T was cooking up a faster "Max" 18Mbps/1.5Mbps U-Verse tier. Today the company made the tier official, a press release confirming that "Internet Max 18" will be available to eligible residential customers November 9. The tier supplants AT&T's previously fastest 10Mbps, and is $65 a month as part of a TV bundle. We ask AT&T how many customers will really be eligible for the new tier, and whether bandwidth may get a little tight.

While most customers can only get 25Mbps from AT&T's VDSL service (both TV and data), many sit closer to 5,000 feet, where 18Mbps over a single VDSL pair won't be possible. Some customers close enough to the DSLAM (we're talking 1,400 feet) have seen their U-Verse gateway sync at 100Mbps. We've also seen customers at 1850 feet sync at 58mbps, and so on down the line.

Distance is going to limit this tier's availability, but it's not yet clear how much. In conversations with AT&T, they weren't able to provide us with a loop length cutoff qualification point, though AT&T spokesman Seth Bloom insists to me that "the overwhelming majority of our U-verse eligible customers will be able to order Max 18."

How could that be possible? AT&T is going to provide 18Mbps even to customers with a 25Mbps line, but that speed will only be obtainable when the TV services aren't in use (or are being used less). The move explains AT&T's recent reconfiguring of their terms of service. However, it's going to raise some customer eyebrows when the 18Mbps tier they signed up for is only 18Mbps when the kids are asleep and hubby isn't watching the 50" Plasma.

"The rate required for a video stream is not constant," explains AT&T. "We use the most sophisticated compression technology available that encodes video at a substantially lower rate than our competitors, and we also use variable bit rate encoding," says AT&T spokesman Seth Bloom. "The rate varies based on the picture being displayed -- higher rate for high detail or high motion image, lower rate for an image with less motion or less detail."

"We know that even during the hours of highest activity, the vast majority of our customers aren’t watching 2 HD shows, 2 SD shows, and using maximum broadband speeds all at the same time," he says. "There’s plenty of bandwidth and flexibility to be able to offer Max 18," Bloom insists.

The new tier is primarily a marketing counter punch against Comcast, who was using the cable company's 16Mbps "Blast!" tier as a tactical weapon against AT&T in U-Verse markets, where some Comcast employees tell us they're paid $100 to spot fresh U-Verse installs. Comcast's new 22Mbps and 50Mbps DOCSIS 3.0 tiers leave AT&T one step behind, and does nothing to derail the argument that AT&T should have simply invested in pure fiber to the home.

Still, AT&T probably figures that their current speeds are more than adequate for the majority of customers for several years. The company is working on 30-40% faster speeds at greater loop lengths with bonded VDSL, but it's looking like that won't be available until late 2009. Keep your eyes peeled on our U-Verse forum for user experiences (specifically TV crowding and distance) with the new faster tier when it becomes available next week.