SIR - I understand why Gerry Roberts and his wife"shout something inappropriate" down the phone at a scam caller. (Sympathy over cold calling annoyance, Craven Herald letters, October 4). The advice from BT is to put the phone down after you say "hello" etc. You check the number. Often, it appears to be a UK number. Enter 1572 and agree to put the number you've just answered into the junk box. That number cannot be used for a scam call again on your phone. There is a certain satisfaction in knowing that. I do not yet see the advantage of acquiring the "display" phone, recommended by friends.

In the two weeks since my last letter appeared in the Craven Herald (September 20), I have had six more scam calls, making 18 in 10 weeks. The last two I had, on October 2, were "silent" calls. I answered the second call; the first came in the morning when I was out. When I picked up the phone, there was silence, followed by a click and then the line went dead. No doubt, the caller wanted me to ring the number back so I could be charged a huge sum for the phone call. Instead I entered 1572 only to be told the number was "unrecognised" and could not go into the junk box. An "unrecognised" number is a made-up number and is different from "number with held" and "ex-directory". Even BT do not know where "unrecognised" numbers originate, or if they do, they are not telling.

I then rang BT and the operator blocked the "unrecognised" number for me. He then told me I had had a similar call in the morning and proceeded to block that number too! I did not need reminding that scam callers are getting increasingly sophisticated. I suspect that the "silent" approach is tried when the intended victim has repeatedly refused to engage with the voice at the other end of the phone. We need to be vigilant and determined not to be undermined.

Kathleen Kinder,

Northfields Avenue