Gary the problem you mention about overseas callers is also a massive one in Europe and the UK. I wonder how the BT phones cope with calls from caller that have witheld their number - there is no number to block and this has been a problem I have had with my iPhone, sur I can block numbers but if the number is withheld then I cannot block it! 2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
2018 Melting Silver Mini Countryman PHEV - soon to be replaced
2015MY Corris Grey SDv6 HSE Dynamic, the best car I have ever owned, totally reliable only a cou0le of rattles in 3 years, now no longer in my care
Also in my garage is a 1996 TDi300 Defender 90 County HT made into a fake CSW

I may be wrong but I think with the I Phone you block the caller after it has called you the first time and if its "withheld" it then has no number to block. With the BT system I think it just intercepts any call that isn't on your approved list and the cold calling systems either can't be bothered to go through the process of getting through to you i.e. giving a name and waiting to be authorised or just don't like connecting to a computer.

All I know is that the BT system is a godsend since I have started working from home. Worth its weight in gold!

Thanks for all the replies. Invested in the BT system and it works a treat.
Very happy with my new phone set-up and seems like money well spent

BT system is money well spent  2016 bmw x5 40d m-sport space grey
2015 bmw 335i m-sport touring mineral grey/coral interior looking to change again .
Gone HSE SDV6 Dynamic indus silver, santorini contrast roof,panoramic roof,red brakes,privacy,climate front seats,tow bar great car enjoyed it ����
Gone my10 3.0 tdv6 Bali blue/ivory 5 years 24k no problems great car will be missed