Documentation needed for 2nd hand decoder

[Speedster]

I'm looking to buy a second hand decoder. What documents must I get from the previous owner to transfer the decoder to my name?

 

[IceQB]

Previous owners ID, address, phone number & i think the smart card number (had to use his as i think the PVR smart cards are different to the normal ones).
Thats all i had to supply over the phone.