I have had the same experience as below. I decided to play the same game and called them over and over and over. usually hang up on 1st ring, other times it rings longer, then the phone was busy (presumably off the hook?)
we received calls from this number (604) 420 3871 caller ID METRONET COMMCT on a daily basis. they don't leave msgs and they don't talk to us.
Just add this number to your "selective call rejection", availabe from SHAW and probably other phone companies as well and they can't bother you again.