Pick up only heard fax noise

This is another number used by telemarketers for Air Duct Cleaning Services. They have called me several times from this number as well as 416-111-3949. As soon as you ask for company information or the callers name or ID # they hang up. I have filed complaints for both numbers with the Canadian "Do Not Call Registry" and have never heard anything from them. I have electric heat so not sure why a duct cleaning company keeps calling. I even tried to book an appointment but they want your credit card information before they will schedule an appointment.