how do I prevent my ringtones from being freely and

[jmsbennin]

unlimitedly distributed by unauthorized persons?

[Deobrat]

The problem that you have got into was faced by many of the digital content providers in the mobile world. Many vendors collaborated and formed Open Mobile Alliance (OMA). They developed something called as DRM (Digital Rights Management), popularly known as OMA-DRM.It allows adding encrypted information to digital media content so as to prevent unauthorised copying/viewing/playing of digital media content.There are tools available to protect your digital media. You can find some really easy (and free) tools if you spend a couple of minutes on Google.

[achtung_heiss]

Just don't let anyone know about them.