I am in the process of developing an app. My question is this: My app will use a sound that is pretty obviously from the iphone. I'm just wondering... is it illegal to sell my app instead of giving it away for free? I mean, it's not my sound, and furthermore it's not my sound on an Android app. Question 2: Is it illegal to make a first app that contains that sound, give it away for free, then make a second app and make users pay for that app, but that app contains both the iphone sound (that you can get for free in the first app) and other sounds? Thanks for the assists!