Will unlocking my iPhone erase my songs etc?

Hi. Switching my iPhone to another network and I need to unlock it first, will doing so erase all the music I already have, plus all my apps and stuff? Ideally I'd like my iPhone to stay exactly the same just with a new carrier. If this won't happen can someone please tell me what to do to get it that way? Right now it has none if that matters. Also it's an iPhone 4.

Just do a backup first in iTunes and you will be fine