DSL service travels over phone wires. The copper portion of the phone wire ending at your house cannot be longer than 18,000 ft (on average, about 3 miles as the crow flies, but phone circuits are notorious for wandering all over town and back). The other end of the copper circuit must terminate in a location that has the proper DSL equipment in it. This could be the main central office or out in the boonies it could be a special equipment cabinet somewhere beside the road. Such a cabinet (remote terminal) would probably be fed by a fiber optic cable back the the central office but it would need to have a smaller version of the DSL equipment in it to convert the optical signals to the electrical DSL signal. Remotes that were installed long ago don't have the proper equipment for combination voice and DSL unless they have been upgraded recently - an expensive proposition that phone companies don't like to do unless they smell a good market at the other end. Newer ones are probably DSL-capable as the extra cost of that vs. a plain voice cabinet is minor. Those are the physical requirements that have to be met or else no DSL service is possible from anybody.
The physical issues are complicated by the business issues. Your local phone company (Qwest) owns the copper. Under deregulation, they are required to permit other qualified phone service providers offer service over their copper. Originally, that only applied to long distance, but now local service is up for grabs in some states. Since DSL is not a regulated phone service, but is an unregulated information service, the phone company that owns the copper may or may not allow other DSL service providers to use their copper. If your copper runs all the way back to the central office, it is probable that some other DSL company has equipment there that can be interconnected - but you'd have to research who they are, not every company with ads on TV has the necessary business relationship for service from your specific central office. If you are far enough out that your phone service passes through a remote terminal, it is highly UNlikely that Qwest would offer space inside that cabinet for a competitor's equipment. So then it would be Qwest DSL (with a requirement of Qwest phone service) or nothing.
The Speakeasy.net offer you showed up takes it a step further. They will take out a phone number in their name but running to your house. It won't work for phone calls if you plugged a phone into that jack, but they will send DSL over it. That's why it is $50-60 - their monthly phone bill is buried in the cost to you. However, you still need to meet the physical requirements above and Speakeasy.net has to have a business relationship with Qwest for the proper equipment in your specific central office.