There is a tech solution that looks pretty good to me. Look up the free
and open software package called NCID (network caller ID). You set up a
whitelist and a blacklist. If NCID matches a number on the whitelist, it
does nothing and you can pick it up or let the answering machine take
it. If it matches a number on the blacklist, it will hang up after a 0.4
second delay. You can abbreviate the numbers on either list, so you
could whitelist all numbers in your local area code or even whitelist
just the area code+exchange(s) in your city. You could whitelist only
your out-of-town friends and family.

There are no pre-existing limits on the length of either list. You can
also install a third-party module to record (in a simple database) all
the caller ID information of the numbers you hung up on, time-stamped.

NCID requires minimal hardwa Pentium II, 256M, cheap USB modem with
caller ID capabilities, a small hard disk or thumb drive and some kind
of Linux. You will need to install from sources.