By default, Apple's iPhone has one ring tone set for all contacts in your phonebook. If you wish, however, you can set ring tones for every contact stored on your iPhone so that each person has his own specific ring tone. If you want to set different ring tones for different people on your iPhone, you can do so in a few steps.
Tap the "Contacts" icon on the iPhone's home screen.
Tap the name of the contact that you want to assign a specific ring tone to. Tap the "Edit" button in the upper right corner of the contact information page.
Tap the "Ringtone" option, followed by the name of the ring tone that you want to make theirs. Tap the "Save" option to save the settings.