Dont pick up - they'll know they have a working number if you do. Likewise, Do not call them back with your number blocked and push 1 - it unblockes your number so they can see it. And if you call them back with it unblocked it'll alway show up on there caller ID. they use fake number generators so your phone will show a different number than the one they are really calling from - any number or city they want you to think they are in, when if fact they could be anywhere in the world - even overseas !
Whenever they identify your number as a working residentual (non buisiness) number they will add it to their list, then you'll begin recieving a flood of telemarketing calls from varios fake numbers all hours of the day seven days a week for several weeks. Once you quit answering long distance numbers they'll start faking numbers from your own area code.
No voice...no message...unsolicited call received. Perhaps a class action complaint from this forum to the FCC for harrassmenent, stalking should be considered. Then, a civil action against PAC-WEST TELECOMM for misue of of the airwaves to spam, harrass & stalk.