Ack... I know the feeling
However.. there is a solution and it workd great... I have a special 0870 number that goes straight into music... then i have a special recorded message asking for the name of the person... then the system calls me and tells me the persons name and where there from... then i have a choice of wether to pick the phone up or not... usually not.
If not then it goes into answer machine mode where it emails me a WAV file of the message.
Sweet eh.. and all for £10 a month... so i always dodge those pesky YP salesman.
I got ripped off one for £400 when a magazine company went bust... i swore never to buy anything over the phone again.
Another tip... when the person is on the phone talking... either ask them to hold or put them on secrecy and then put the phone down.... they will never know you have put the phone down and they will sit there for 15 mins waiting.... that makes me laugh because they are usally still in the system and I make 2 pence a miniute from the call.... great beer money!