They ask for your SIN to confirm your identity. This number is not a scam at all. They do not ask for SIN numbers anymore anyway. If they ask for you by name, then you owe the government money. Pay your bills people.
The gov would never call themselves the ccra. They are the cra (Canada Revenue Agency)They would never ask for a SIN because they know it already, this is a scam.
I think the request for your SIN was so they could pull up your file.
The guy who called me had the most ridiculously annoying canuckian french accent, he actually sounded stupid. If I could have reached into the phone to slap him I would have.