TPS only works (and not perfectly anyway) when the number dialling is in UK. It can do nothing at all for numbers dialled from call centres or by computers that are based outside UK. Lots tend to come from centres in India or Philiipines.
We were plagued by these calls - which seem to come at a peak of around 5-7pm, and a few early morning!!!)- but a new phone with a nice Caller Number Display and a relatively short (3 rings) activation of the voicemail message seems to have dramatically cut the number of such calls.
The voicemail message is a fake ie it indicates that the caller has reached the number of a business (totally bogus name which for fun I cange periodically) and that "if you leave a message and number we may get back to you". Almost always the phone call ends INSTANTLY at that point.
All of friends have been warned of this message and to just ignore it and leave a voicemail as normal. Our friends also know that because of the short (3 rings) before voicemail kicks in we are likely listening anyway and that soon as they start to speak on voicemail we will pick up the phone. So much so that friends now start voicemail messages with such as "Hello Snod are you there? This is XXX" shift yer bum and answer" or something similar. Our friends are like that!
We have a few friends who call from places in other continents and Caller Display does not always work with their calls so I cannot just block witheld numbers or No Caller ID
Set up I have works fine so far as we are concerned.
Another approach could behttp://www.youtube.com/watch?v=A79RQZWArR8&feature=endscreen