SIR – A new trick by telephone cold callers is to say do not hang up, this is a public service announcement . Now that there are endless government adverts on TV, people are likely to be taken in by this ploy. Cold calling is an increasing nuisance and n

SIR - A new trick by telephone cold callers is to say "do not hang up, this is a public service announcement".

Now that there are endless government adverts on TV, people are likely to be taken in by this ploy.

Cold calling is an increasing nuisance and no notice is taken of Telephone Preference Service requests that a number should not be called.

A way for BT to deter these pests would be to terminate the number withheld facility which they always use. There can be no legitimate reason for using this facility.

RICHARD DURRANT

Park Avenue, St Albans