Specific ringtone for callers not in the phone contacts

[dual]

I wonder whether there is an application can run a specific ringtone for callers not in the phone contacts.

 

[zuben el genub]

If you can switch ringtones, pick one for default, then group your contacts into family, friends, business and assign separate ringtones to each group. Once you have it set up, it's easy to add a new contact to a group. That way, someone not in your contact list will get the default ringtone. Businesses with several lines will be harder.