Despite Verizon's announcements to the contrary, it appears that you still need to have your voice landline connected in order to continue having DSL. I discovered this after getting fed up with Comcast's lack of reliability in my area, and am in the middle of (very reluctantly) getting DSL put back in.
You could, however, drop your voice service down to the absolute bare minimum. In my state (NJ), Verizon has a "low use message rate" tier that costs around $6.00 a month, and basically provides dial tone and nothing else. No calling features, no regional or national long distance, and only about 20 "message units" are included for outgoing local calls (a messuage unit is a local call lasting 5 minutes or less).
It's about as low as you can get if you don't actually intend to make calls on taht line, and at the very least, you'll at least know you can use it to dial 911 if the power and/or broadband internet service fails.
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