They do! Which means that Susan mostly thinks Papyrus is just a guy who says funny things on the radio. Honestly even if he saw him in person he probably wouldn't recognize him at first, but if they actually started talking he would probably recognize his voice after a minute and be able to place it.

Which means that it's not very deep CR or anything, but Susan likes being able to talk to people, especially people who don't talk down to him, which Papyrus doesn't - so even though it's maybe not as close as with some people he's talked to, it's actually probably more positive from Susan's end! Still, he isn't going to go to him for any deep or serious conversations, but as something fun to kill time, or as a way to just chat and have fun during the day when he's bored, Papyrus is definitely someone he likes talking to.