Get a Google Voice number in US (217) area code

I want a Google Voice phone number that starts with "217." New Google Voice numbers in the 217 area code (central Illinois) are currently unavailable. However, some people already have 217 numbers from when they were previously available. Either find someone willing to part with their 217 GV number, or find a method for porting to GV a 217 phone number that I can get through other means. The Verizon number I have currently is (217) 549-2737, but it can't be ported to GV directly. I know that Sprint and Google have an arrangement which allows Sprint customers to use their Sprint number as their GV number. But I want a true GV number without a carrier.