alan_m submitted this idea :
I too have a Trucall with zero cold calls put through and none on the answer
phone but the logging suggests up to 10 dropped calls per week and this is
confirmed by an old technology caller display box which also logs all calls
(mainly withheld and International).

It is TrueCall system combined with the handsets, it logs every
outbound call and every caller, whether answered or not. If a call
comes through and the call is blocked, it puts it on the display as a
number of calls blocked so I can review them. There were several per
day when I first installed it (which was why I bought it) - that number
had declined to the point where now we have had an entire 7 days with
not a single call.

As the callers now mostly use an automated system playing recorded
messages, it seemed odd that their systems should notice they are being
told to go through an automated process at my end, to get through - and
that this should deter them from ringing. At my end, it will ask them
to state their name and press #. If they manage that, my phones ring,
their name is played back and I then get the choice to take the call,
ignore it, or pass it to the voicemail system. None of the nuisance
callers ever got as far as making the phones ring or getting manually
rejected.

Everyone who's number is in my phonebook, gets put straight through.