Is it possible to back-up content that you didn't buy on an iphone?

My friend gave me her old and broken iphone. After fixing it up a bit, I was told to unlock the phone I would need to erase all the content first. Is there a way to back up the content that I didn't buy?

Added (1). I've already paid for the unlocking service. All I need to do is erase the data and I'm good to go.

Yea use iphonunlocker.com, their software is the best for iphones.