why doesn't Android allow a special ring tone for "suspected spam" calls?

[AC Question]

Android's feature of making the whole screen red when a call is suspected to be spam is great. Thank you Google!

Even better would be allowing the phone owner to set a special ring tone for all such calls. This would eliminate the need to pull out the phone and look at it when a call is likely to be spam.

 

[hallux]

Because the phone doesn't know if the call is suspected SPAM until after at least one ring. The phone/dialer does a search of sorts when it's detected the number and then displays the result as suspected SPAM or not. That's also why you'll sometimes get one ring then it stops, the phone chooses to block a known SPAM number once it's done the search.