Thank you for your reply. I don't really want to add numbers to a "blocked" list anyway. What I would like to do is to set up the phone such that any incoming phone number that is *not* in my Contacts goes straight to voicemail. This feature is available on my VOIP landline, btw, and it is a Godsend.
The inference from your reply is that no such feature is available on the iPhone itself. Blocking spammers one number at a time is not very efficient. Changing phone numbers is of course totally impractical, since it would require me to notify all my contacts, and expect all of them to correctly change their contact info, and also there is the matter of the large number of websites etc. that have this existing number as my contact info.
A. Is there a way to request or suggest features for future releases of ioS?
B. Do you know of an iPhone App that might be purchased that performs such an operation?
It would seem that programming to do this is fairly straightforward. The iPhone is already capable of conditionally dealing with calls differently depending on time of day. This is conceptually similar, conditionally operating on the call differently depending on whether the originating number is in my Contacts or not.
Anyway, one way or the other, thank you for your prompt reply.