Please explain... Is "Flashing" a phone after rooting it the same thing as buying an unlocked phone and making it work with VM?
I really do not want to mess with rooting, I am just curious...
MoNameFace's answer is correct, .... mostly.
I think he meant by "flashing" was taking a phone from any other carrier and faking the VM system into thinking you are using one of their phones.
The VM system uses certain info that your phone sends back to them, you can fake that on a phone. Some Sprint phones can work this way on VM, but usually not very well. Doing this breaks numerous FEDERAL laws.
I'm being vague, while still trying to give you an idea how it works.