i very very much doubt that anyone from topp's paid campaign made the call, indeed, i find it highly unlikely that topp even has a montreal office from which people would make calls. if it was a montreal number and the person sounded at all professional, it was probably issue from the famously affordable opinionsearch. what would have happened in this case is that the worker would have had a script, but may well have gone off script based on his/her own views, or even just what they'd heard from the last person they talked with.
most likely, topp's campaign manager (is it himself?) has volunteers calling from either their own portable phones (which would explain the montreal number as a local number from a recent transplant to montreal, almost certainly from bc or ontario) or google chat/skype/a paid hosting service (which would explain the montreal number as a clever ploy to make contacts believe that the call originated from a locality in which the candidate is unpopular). so it could have been a topp volunteer calling out of toronto or vancouver, or some concordia student (or, i'll darkly concede that a mcgillian or two also might be supporting m. topp) calling from a phonebank meet-up in some living room or whatever.
essentially, you can't blame the candidate for a call like this, he couldn't have had anything to do with it, and every campaign attracts supporters who'll apply pressure in whatever ways they believe may benefit their candidate the most.