Ok Meg. I don't want to get into an argument with you, but you do not have to "flash" the phone. It is very straight forward, no messing with the software, no jailbreaking. Put a Sprint iphone 4 MEID into the website I mentioned, and you will see it is supported. you will get a slightly different message though, probably because this is a CDMA device only. Here is the message:
If you put in a device that is not compatible with the network, for example, an ATT iphone 4, you will get the following message:
The phone associated with the Device ID you entered is not compatible with the Verizon Wireless network.
So far, the website has been accurate as to which devices are able to activate, and function without issues, from my personal experience. I have probably tried 50-60 phones on that website so far, and tested the fundamental features out. I only speak in "matter of fact" ways when I have personally been successful at doing something..more then one time! So you can believe what you want, Two years ago, I activated two Sprint iphone 4 on the Verizon network, and one last year. They "officially" did accept the phones. NO FLASHING! So you can take it for what it is worth. :-)
Here is a bit of advice to anyone. When you call a "company" always remember, that you are not talking to that company, but you are talking to an individual. Companies have rules, and policies, but the "official" policy of the moment comes from the person on the other end of the line. Call back, talk to someone else, and the "official" policy can change. You are not calling Verizon, you are calling a person, so the answers can vary widely!