Distance from CO?

Its probably disabled because they don't have the data necessary to provide anything close to reality. The facilities based LECs have deployed remote DSLAMs all over the place in hundreds of satellites in each of the many hundreds of rate centers all over the country, and you really need to know how far away you are from a remote DSLAM, not the CO. Since the LECs don't publish that info (unlike where everybody knows where the COs are), knowing the distance from the CO to you tells you nothing.

The only way to really know what you can get is to talk to the LEC to run you through their prequal system, which does take into account all the remote equipment in the field, not just a pure CO to you distance loop, but as I said, this info isn't public.

Don't forget that if you're not an ATT customer (if you have DSL through someone else) that even though they're the last mile provider, you're gonna have to get that information from your provider, ATT won't even talk to you.