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.
