Just out of curiosity where do they get addresses and phone numbers for letter writing and calls?
There are several websites which store the info that used to be in the phone books that dinosaurs like us grew up with.
One is "Whitepages. com". It has a "reverse address lookup", enter the street address and it tells you who lives there. If there is a landline it will give that to you too. Accuracy is questionable, but it's at least a starting point.
There are others which work similarly.