Genevas daas- because often they mask their number and have you think it’s someone else so that you pick up.
Bittul zman (and or gezel shena)- self apparent, phone ringing wakes you up and you don’t want to be woken up even if “the gates of shamayim are closing” (to quote one of the telemarketers). Bittul zman for the same reason.
SO you’re saying that they’re actually stealing your telephone lines ability to function properly, that’s for you to call out and people you want to call, to call in! That’s like harassment and trespassing.
