Autodialers with recorded computer babble ("Please select which flavour of spam you prefer from the menu..."). No way to block them. You can politely (but firmly) request they de-list your number and never call it again, and sometimes - sometimes - they politely accede. You can rudely demand instead, but usually won't get productive results unless you can (and will) follow up with official complaints to your carrier and the CCTS.
Otherwise your only options are to register on the Canadian and USA Do Not Call Lists (which are somewhat helpful and somewhat useless, because they only prohibit legit and compliant spammers) or to get in the habit of not answering unknown callers. If important then they'll leave a message, if you never return calls then they'll eventually give up.
It would be nice if PM could implement some sort of network-side Blocked Incoming Number option in Self-Serve or Voicemail user options, with or without playing back any (polite or rude) automatic/recorded messages to the unwanted callers.
It's become evident that Telus hasn't yet implemented a working UNCB filter to shutdown spoofed or blacklisted calls. Autospam is a growing problem which needs to be addressed with better user controls than ineffective device-side software blocking.
