Here's an example of one:
http://www.linuxdevices.com/news/NS3554579085.htmlIt's 'just' a network card, for a very 'expensive' high-bandwidth connection, probably between telco equipment, or to a high-rise that runs its own ISP/telco or something. (Like most telco stuff, it probably runs ATM as a protocol, and the number of IPs that can be apportioned depends entirely on the routers at each end.)
As an example -- and I have no idea of the accuracy of this -- the DS3 might terminate at a router in a RT (Remote Terminal) containing a DSLAM (DSL Access Multiplexer), and the DSLAM by nature or programming limits the bandwidth available to each user, while of course it can still be oversold (sell 50 people DSL with a T1-grade link speed, but have the bottleneck of the line that can only support 28 users concurrently without forcing the router to queue or drop, and some of that bandwidth is dedicated to providing voice service as well).... Or the DS3 could pop straight into a megacorp's router, and it's up to the company what they do with all that bandwidth and what routing/IP block arrangements they've negotiated with the telco.
It could also be run between the local CO (Central Office) and wherever the telco found convenient to offer their colocation cage(s),* which is what seems to have happened here... someone had access to, or broke into the "colo," and managed to walk out with some expensive equipment that wasn't theirs.
(Not sure what you'd mean about home users, but in towns smaller than NYC, you'd expect the colo to be in the same building as the Central Office that provides the residential service(s) and so on. Manhattan is huge, so they probably have a couple facilities, one at the 'CO' for the third-party ISPs to provision their DSL, and at least another just for the 'colo' customers who want to put a server near a fat pipe.)
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*Sort of a literal cage; apparently they're usually 'secured' rooms, with jail-like bars for show, and a guard around to let you in and make sure you aren't ripping the cables out of other people's racks. I'm sure Wayne or someone can elaborate.