Just call them back, wait on the line and with a firm tone say "By law you have to stop calling me upon request. Please remove <your number> from your call list immediately". They'll ask you if you are someone (for me it was Dina) just say no and they'll remove the number. If they don't, they are breaking the law :)

robocall from a collection agency.  calls begin at 8AM and stop at 8PM monday to friday and are spaced out about an hour apart.  picked up a couple of times and you get an incoherent robotic message and then you get dead air.

Just do what I did call them back over and over don't say anything or they'll use it against you but keep doing it eventually they'll get really upset even threaten calling the cops but even if they did the cops would tell you both to stop calling each other LOL They love it just relax watch some t.v keep hitting redial and mute =] If you get bored too feel free to scream into the mic or get your friends to join in for some good old fashion fun ^^

Not sure it's a collection agency..I answered it and recorded message of a female voice started rambling off a number "1 billion 9 hundred thousand and something and repeated itself 3 times then the line went dead"

If I have to make a trip to Vancouver to meet anyone from that calling center to re arrange their face, I will.