It seems likely that this is the Canadian Cancer Society as others have posted. Please note that they are required to keep 'dead air' calls to a minimum, so if they call and the line is dead - YOU CAN STILL REPORT THEM. Just be aware what you're reporting them FOR.
Calls up and asks if so and so live at the residence.
The woman at the other end said she was with the Canadian Cancer Society.
They were supposedly calling in order to recruit more door-to-door harassers.
I have no idea if this is true.