hbruun, Please don't cross post your questions. You only need to ask it once around here. If someone knows the answer, or can point you in the right direction, they will. But we don't need multiple conversations running on the same question. Thanks!
Now, on to your question:
Yes, an unlocked Audiovox will work just fine on Cingular. However, buying an unlocked version might be a little hard to find. You will have to purchase one, and then find someplace that will unlock your phone.