Magazine subscription scam.
The company responsible for the calls is Millennium Marketing Group, they have several other fictitious names like Magazine Source, Publishers Renewal Service and Budget Marketing.
Besides phony magazine subscriptions, they also sell worthless invention marketing contracts.
If you don't want them calling you, they can be contacted at:
Millennium Marketing Group, Ltd.
10550 Marty Street
Overland Park, KS 66212 USA