Aha, nuisance calls. I managed to stop mine by cancelling my landline. Seems to work perfectly.

My data now comes from cellular, even to and from WCG. Some S*ms*ng mobiles also have a number block feature which I found useful when my car dealer pestered me for business. Nuisance woes are yesterday!

There is a landline gizmo called Callblocker http://tinyurl.com/lhua989 which I found effective, but costs money.

Incidentally, I'm of the view that the Plain Old Telephone Service is now all but obsolete for many, though it's often needed for a conduit to transfer ADSL. I'm fortunate in living 100 metres away from a cell mast, so in addition to being microwaved 24 hours a day, I get 11 Mbps data without the copper wire and the huge telco bills.