What she wants is "bare DSL" or "naked DSL", but it's not up to the internet provider (in her case DSL Extreme), it's up to the phone company. Her phone company has its own internet service that DSL Extreme is competing with, and the phone company owns the lines that DSL Extreme uses. The only reason the phone company allow this is because the FCC requires them to. The phone companies really aren't going to like the idea of not making any money off of Julie at all, and most likely will fight it.
Leo's advice would be for her to call DSL Extreme and tell them she wants to do a "dry loop" (use of their lines with other services), and ask what their experience has been canceling phone service with her carrier in that area. She should ask for their help because DSL Extreme would love for her to do this.