The "local" exchange calls are largely to our land-line...which is needed for our alarm system, but also it's the one that my elderly parents insist on calling. While they are still with us, I can't really change it.
As to the law, this activity is already "not kosher". Unfortunately, technology has hampered enforcement because random, spoofed caller ID numbers combined with the robo-dialer being anywhere on the planet (and thus, outside of our jurisdiction) is a tough thing to combat.
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The most expensive tool is the one you buy "cheaply" and often...