This is a fraud campaign currently active in Canada using a series of Iristel VOIP numbers. The objective is to obtain your credit card number and drain your account.
If you attempt to "opt out" your number will be confirmed as live and added to a suckers list for repeated future calls.
God a call from this number today May 10/2013 -- scam - scam - scam claim I won a trip, this is the message left as I did not pick up because it was a strange number.