Not having had a scam call on my land line for a few months, I have now had two in the last two days, both by women with Indian accents claiming to be from BT Internet and that my internet was slow and needed sorting. Almost certainly from the same scam centre. The usual "fix your PC" scam in fact.
I have done some scambaiting in the past (my record is 40 minutes) and have an old WinXP PC set up as a honeypot. I would let them loose on it (they would find nothing but Indian p0rn), but it is not close to my landline phone so I asked them to phone me back on my mobile, but in both cases they promptly put the phone down. I have also found this with scammers on Mrs Lucan's mobile (which she hands to me - the loft insulation scam mostly) - scammers have become very wary of the slightest sign of being baited or strung along; yet I do my best to sound genuine. How does one get them to stay connected? Perhaps I don't sound senile enough for them.
I added the numbers to the Who called me? website, not that does anything effective and they spoof different numbers all the time anyway, but it allows you to do something. With scams that originate from abroad the police there don't care and the UK police cannot do anything - in any case the latter say they have more important things to do despite many people being scammed out of their life savings. In India at least, you can only raise a legal case if you are based in India yourself, and if you watch the detailed scambaiting videos it is apparent that many scammers manoevre their victims into giving them money rather than taking it directly, so they can argue it was not theft - even if it did ever go to court.