The problem is,that although you may be ex directory,these centres have phone number generators which just make up and dial numbers at random.As the other guy Andy says,the telephone preference scheme will help.These call centres are usually with-held numbers and I believe there is a program available somewhere which blocks calls from with -held numbers.Myself? I just have my answerphone set to come on after one ring,with the message"If you are a call centre,leave your number and I won`t get back to you"