How to Set Ringtones and Text Tones on iPhone
You can set iPhone Contacts to play a unique tone when you receive a phone or FaceTime call from a particular contact. For example, if you want to be sure you know instantly if your spouse, sick friend, or boss is calling, set a unique tone for that person.
Tap to add a new contact or select a contact in the list of contacts and tap Edit.
Tap the Ringtone field, and a list of tones appears.
Tap a tone, and it previews. When you hear one you like, tap Save.
Tap Done to save the new tone setting.
If you set a custom tone for someone that tone will be used when they call or FaceTime you. You can also set a custom text tone to be used when they send you a text message; tap Text Tone instead of Ringtone in Step 2 above and follow the remaining steps.
If your Apple devices are synced via iCloud, setting a unique ringtone for an iPhone contact will also set it for your iPad.