BT Call Protect
On Sat, 09 Sep 2017 15:31:44 +0100, Indy Jess John
The usual arrangement mentioned in newsgroups is to buy the BT phone
that has call blocking, because that blocks specific numbers you put
in, allows through all calls from numbers in your callers list, and asks
withheld numbers to identify themselves, only allowing through any that
do. That type of phone works on anybody's phone service, and the
"identify yourself" feature is not part of the BT Call Protect service.
 I can't remember the type number, but no doubt someone who has got
one will chip in.
It's called "BT Callguard", and is a feature of the 8500 and 8600
phones, and apparently several others now, since I bought mine. A
quick search on Amazon suggests that it's becoming standard on BT
phones. You won't need to sign up for any extra services if you have
one of these. The phone does it all.
The system works best with CLI, because calls from people in your
phone list will be identified and passed through as normal without the
announcement asking them to say who they are, but it's quite capable
of working without it.
I haven't had to answer one single spam call since I got my phone
several years ago, literally none whatsoever. Their numbers (when not
withheld) appear in the call log, so I know when I've received some,
but every single one of them so far has given up at the Callguard
announcement. If a caller doesn't identify themselves at this point,
the phone doesn't even ring. The system really works.