No audible caller ID on IPhone 5

I can't assign ring tones in contacts in my new iPhone 5.  Data, including contacts, were transferred using ITunes backup from my old IPhone 3G.  I had assigned unique ringtones to all of my favorite callers.  Contacts in IOS 6 has no field for ringtones.  The only place I can select ring tones is in sounds, which assigns the same ring tone to all callers.