[asterisk-users] Best way to detect unknown and/or private incoming caller-id?

[voiplist]

I am aware of how to match a particular caller-id or a caller-id
pattern and do something with the call like this:

exten => 15554441212/_888NXXXXXX,n,Playback(GoAway)


What I am curious about, is the best way to block unknown, private and
000-000-0000 calls.

I know I can do this for 000-000-0000 calls:
exten => 15554441212/0000000000,n,Playback(GoAway)

Is there a better way to catch calls which are purposely blocked by
the calling party? Sometimes they come through as 000-000-0000 and as
I recall sometimes just blank or unknown.


Regards,
 Todd R.

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