Yikes, Digium has announced a DS3 card for Asterisk. So, the next time you need 672 channels of voice data all on a single PC, you know where to go.
It’ll be interesting to see what they’ve done with this–their current T1 cards have compatibility problems with some motherboards and have extremely tight timing requirements. In general, you don’t want to try running more then one of their 4-port T1 cards on a single PC. Since a DS3 carries 28 T1s worth of traffic, they must have done something to clean up their designs, or there’s no way it’ll be able to keep up with the load.