Technically it is very easy to do. If you can get to the program menu of a CDMA phone then you can program in a new phone number and SID. But you can't change the ESN. The new provider must give you a new phone number and SID to program into the phone AND all that data must be input into their system and recognized by them exactly. Any CDMA phone operating on the same frequencies can work on any cariers CDMA service. The problem is most carriers simply by company policy refuse to activate any CDMA phones that arn't currently on their list of ESN's for their phones. It's not that they can't, it is that they wont. Also if you start screwing around in the program menu without the assistance of your provider to recognize the changes you will just end up messing up your service.

This basically makes trying to unlock a CDMA phone kind or pointless if you are trying to jump ship to another CDMA carrier with your phone. The only companies that I have found that were quasi-willing to activate someone else's phone are some prepaid MVNOs. Best to call and ask the new service if they will activate the ESN before you spend money on the phone.

one of our mods, Brad, did some research on the topic... while it is technically possible, you would have to have a Sprint representative with some technical knowledge who is willing to bend a lot of rules for you - so it is improbable

Is it possible to purchase a Verizon phone and if you can get it unlocked will it work on Sprint? Like the 700w?

I've been with Cingular/GSM and so used to just taking my sim card that I have no clue.