How can I change ringtone for "Unknown" callers with no caller ID?

[jjaakk]

Strange one this. I recently set a notification tone in the Desire.

Unfortunately, this notification tone is also used as a ringtone for incoming calls with a caller of "unknown" and no caller ID.

How can I set the "unknown" with no caller ID ringtone to be my default ringtone ?

 

[coordinatezero]

I'd be interested in this too. My old BlackBerry Curve could do this (default tones for Caller ID vs. no Caller ID, but then individually-settable ringtones per contact).

Someone in another thread suggested putting the "unknown" ringtone as the default, and then adding every contact into a group with its own ringtone, but I can't find a way on my EVO to set a ringtone for a group...??