We have the BT8500.
You add the numbers you want the phone to let through - you can add others at any time.
Call comes in - if its in your stored or allowed numbers the phone rings as normal.
If its an unknown, withheld, international number then the caller is asked to say their name and press #
The phone then rings and you hear the message from the caller eg. Joe Bloggs
If you know/want to speak to the caller you press 1 on the phone and you then have your normal call. If not, press a different number and the caller gets told that you don't want to take thier call!
If a call comes through and there is nobody at the callers end to speak and press #, then the phone disconnects the call.
You can add numbers to a blocked caller list.
We have the phone and the corded phone, so we only get 1 ring before the BT phone handles the call.
It used to be "grrr another of those calls". now its "I wonder which one that was"!