I actually work for AT&T but only handle the old Southwestern Bell Area (aka TX, MO, AR, KS, OK) but I can't imagine that it is that much different.
I know that in the territories I handle we do have a service referred to as Dry Loop DSL (sometimes referred to as HSI Direct) I believe its either $23.99 or $28.99 (depending on speed). I don't know if it is available in MI but it's definitely worth checking on.
Back when I worked for the OLD AT&T (confusing isn't it? It is for us too!) and I sold local service in MI, I remember MI having terrible taxes, I think you guys pay like $3 - $4 extra in taxes then most other states, which is awful because average taxes for phone are $10-$12 extra per month. (which BTW I think is insane) Meaning you are probably paying more for taxes then are for the cost of the phone line.
Some things to consider before dropping a phone line entirely though. Your home phone is free, meaning you are not charged per min for making local calls, or if someone calls you. Your home phone will work even if you have no electricity (with a corded phone). Also keep in mind that when you call 911 your address will transfer to the 911 operator when you call (some cell phones do this now too though).
Jennifer