More agreement for TPS!
And also, you can get caller ID - with BT this is free. We don't pick up the phone for if the number shows up as withheld, international, or an 0800/0870. If it were anyone important, they'd leave a message.
They always hang up when the answerphone kicks in
For really persistent beggers, if you get the number you can Google it. We had an 0870 number that was calling us up to 8 times per day. The only time I did pick it up - because I wanted to tell them to PLEASE STOP - there was nobody there! They had automated dialling that called more numbers than they had staff, so only the 'lucky few' got an actual person to talk to at the then.
On Googling that number there were lots of people having the same problem. I reported it in to OFCOM via their website - they don't actually look at individual complaints but if they receive several complaints about the same number, that's when they look in to it. Calls stopped shortly thereafter