If like me you have been receiving loads of unwanted sales calls then ring the telephone preference service on 0845 0700707 you can be put on the register free of charge and in about 28 days the calls will stop.
There is also a number to ring for unwanted silent calls (when you pick up the phone there is no one there!) Register with silent call guard on 0870 4443969 or go online to www.tpsonline.org.uk.