The iPhone let's you choose a default ringtone for incoming calls. You can also have the iPhone play a ringtone you choose specifically for someone in your Contacts. So, when that person calls you, the chosen ringtone is used instead of the default one.
- Open your Contacts list by launching the Contacts or Phone app.
- Tap on one of your contacts to view their Info.
- Next, tap the ringtone field. You will see a list of the ringtones on your iPhone.
- Tap a ringtone to assign it to the contact.
Now, when that person calls you, you'll hear the ringtone you chose specifically for him.