Nix.nu. Nix is Swedish for “Nope”, and also the name of a registry, with which you can register your phone number. Call 020-27 70 00 from the phone you want to have registered as “not callable for marketing”.
Instructions: How to register with Nix.
Bonus reflection: Is direct tele sales a dying art form? More and more lackluster for each botched call, it seems.