As far as I can tell, it really is according to what service you go with as to if e-smith and your DSL will get along. I currently use e-smith 3.1 with my aDSL from Telocity and so far it has been working wonderfully ("it" meaning the e-smith server, not the telocity DSL). I did have some problems at first but found out that they were completely on the part of the service and had nothing to do with my equiptment. (They had a router that wasn't on speaking terms with the ATM cloud.) they seem to have had a time getting any DSL working in my area.
Anyway... here is how Iam set up:
many xDSL companies use an internal "modem"/"netcard" thingie. I have no info as to how to get one of those to work or if it is even possible. My DSL service uses an external modem that connects to the outside of my beloved (even more so because this is the one at my home) e-smith communications server! from there it is a standard "dedicated access" server/gateway.
what confused me at first is that the service providers people know squat (if that much) about Linux, or drivers, or netcards, or nat, or masq, or... well the list goes on and on and on. I talked to every DSL service provider in my area before I found one that could say "Yes, it will work with *nix" and not be odviously guessing. SO... ( i do have a point somewhere around here) keep your eyes open for those who will tell you "Hey, I hear linux works with network stuff. It's really just a network card... kinda" and if you can, (just like regular modems) try to go with an external if you can find one. Last but not least, call the tech support for the service provider TWICE! that way you can gage if they really know, or are feeding you a line of... (insert expletive here).
(cryblood puts soap box away)