Apparently the TPS doesn't operate on calls from overseas, so a lot of companies are switching to this method. Even if it looks like a UK number calling, they can, I am told, 'piggy back' on to a UK line and get around the regulations. A new twist someone alerted me to yesterday is when 'private number' appears, it's not a private number at all, but a call via VOIP (Skype or similar) which is another way around the regulations. I either press the disconnect button, or pick up the 'phone and ask who it is and in my gruffest voice say"we are on the TPS and do not want any further calls from your company". Also, I am informed that if you have dealt with a company before, say by ordering something on the internet, you are in effect giving them carte blanche to call you and offer you other goods and services.
M.