Cold callers can be annoying but also rather fun. They usually ring to ask you to switch your energy provider or broadband connection. There is a simple and effective method of dealing with them.
Firstly they will ask if you are the homeowner. Always say 'no'. It is imperative that you do not expand on this simple negative. 'No' will suffice. They will then ask if they can speak to the homeowner. Again, reply 'no'. They will then ask if you are a relative of the homeowner. Reply 'no' [can you see a pattern forming?]. At this point you might be able to discern a faint hint of frustration in the voice of the cold caller who may go on to ask if you are a friend or neighbour of the homeowner. Reply 'no'. The cold caller will then ask you who you are. You now have the cold caller in the palm of your hand.
A burglar. [My personal favourite]