The hall I went to had colored territory cards. Inside each plastic sleeve, there was a "do not call list". That was years ago, so I would think they have upgraded their system.
My favorite story about the territory sheets and the records, was there was a sister who spoke English as a second language and she use to write "not interesting" next to the numbers instead of "not interested". I loved that and a couple of times used the on JWs when I would run across them in their street work. I would put on my fake accent and wave my hand in a "no" fashion and say "not interesting". Of course I am the only one who got the joke, but come on, if you cannot laugh at your own jokes who will do it for you!