Unlocking a sidekick

How can I unlock a sidekick to work on sprint? Sorry I don't know much about cell phones and I want to get it to work with sprint. I won't have to get new service or anything will I?

Sidekicks are hard coded to only work specifically on T-Mobile's network and with the Sidekick data plan. Everything a Sidekick does comes from the server (Which can be a bane if you turn it off and on in a place with no data signal) and this is locked down extremely tightly.

If you can write a program for the Sidekick using the SDK, you can request a dev key, but then you'd also need to try to write software to unlock it, and that is unlikely. Even if you managed to get it working on Sprint's system, it wouldn't be able to access the back end servers to acquire its contacts or anything else, so it wouldn't operate.