Stephen Gower wrote:

I recall Peter Strangman (RIP) had a setup on ISDN which took advantage of
the CLI signal coming through (a split second) before the call proper is put
through. If the number was blacklisted (perhaps even not-whitelisted) then
the computer took the line "off hook" and the caller would always get the
busy tone. I'm surprised it's taken such a long time for a commercial
product to come about, and moreso that it seems less sophisticated than what
Peter was doing 15 years ago.

Interesting approach. Thanks, some food for thought!

--
Adrian C