Can you jailbreak a iPhone 4 from sprint to verizon?

Can you jailbreak a sprint iPhone to work on Verizons network?

First off, changing from one network provider to another is called unlock your phone. When you unlock your phone, it essentially means that you arent stuck with the one provider that has locked your phone into its specific network. [If that makes sense… ]

To be able to unlock your iPhone for example, you have to have either a special SIM Card or have it jailbroken. To jailbreak your iPhone depends on the iOS Firmware you are on. You can check this by going into Settings>General>About and scrolling down. If you have 5.1.1 or lower then you have a slim chance of it working. If you are on anything above 5.1.1 you can't unlock your iPhone 4 to verizon yet. You have to wait until a 6.0 or 6.0.1 untethered jailbreak comes out because unfortunatly there's no way to downgrade iOS firmware's at the moment other then with signed SHSH Blobs. [which is very confusing to explain]
If you are luckly on any firmware that is 5.1.1 or lower, you also have to have a proper Baseband [baseband are also known as Modem Firmware's. To find out what baseband you are on go to Setting>General>About>and scroll down to where it says modem firmware. If you are on any of the following with iOS 5.1.1 or lower you can unlock, otherwise… NO, sorry:/
Basebands:
01.59.00, 04.26.08, 05.11.07, 05.13.01, 05.12.01 and 06.15.00.

If you are lucky enough to be on iOS 5.1.1 or lower and have the proper basebands, you can jailbreak with Redsn0w version 0.9.13 Dev 4 and Unlock with the Cydia package Ultrasn0w. Here is a website that can help you with that stuff:

http://www.redmondpie.com/unlock-ios-5.1.1-with-ultrasn0w-1.2.7-old-basebands-only/

If you don't have iOS 5.1.1 or lower and have a different Baseband then those above, you can't unlock of jailbreak your iPhone… For now, but good luck in the near future.
[P.S. Don't update to the newest iOS as soon as it comes out, that can sometimes screw you over pretty bad:/ Look up something called saving SHSH Blobs before you update next time]