I suspect that they have Rogers cell phone list. Are you on Rogers?
I did not have this problem with Telus or Bell, but have had Debt Consolidation and other marketing type calls on my Rogers cellular.
There is a new Do Not Call list in Canada that may help. Don't know if it works for Cell phones, and may not work for calls originating outside Canada.
This number called me twice within one minute. I missed the calls but when i called back there was a recording with a man's voice that said "the number you are trying to dial is unallocated." Kind of creepy! I wouldn't answer if this number tries callling you back.
On 12 December 2008 I was called from 971-307-2014 on my cell phone (other members of my family have been called from this number.) There is equipment and software available to give a non-existent number on the caller ID and this is being used to display this number on caller ID.
I received a Phone call to my cell phone from (971) 307-2014. I was a lady's voice, seying I won a Car. She said: I'm calling from AT&T, you just won a car" Of course I did not answered the call. Question: How this people know my cell phone number?