Catcher in the Rye, Post 5: A Realization of Time Passed

I know there's a lot of changes I could focus on--like the transition from records to CD's to downloads, the amount of time, now, people tend to spend on the internet and in front of the TV, or the change of parenting styles. But, I want to take a moment and focus on the differences of telephone usage. It might be a strange thing to focus on, but it was bugging me throughout the novel. Maybe it's just me, but I find it strange how Holden calls a number of random people he hasn't talked to in years for no apparent reason. He called Sally, Carl Luce, and his teacher, Mr. Antolini. I find it weirder, still, because he ends up (and/or started out) hating them! No one he called seemed to be bothered by the call (despite the surprise of the situation),  except for Luce, but I tend to think that was because of his distaste for Holden, not necessarily the call, itself. It was Mr. Antolini's call that made me think it was something in the times that caused the nonchalance of being called. Despite being called in the middle of the night, when he and the Mrs. were sleeping, he was cheerful and invited Holden to come over right away. If someone called my father/mother, or me for that matter, in the middle of the night, their call would most likely be ignored. If, by chance, one of us answered it, we would most likely be told we were sleeping and to call back in the morning. Sally's call was also strange, in its way. It had been about a year since they'd talked, yet she didn't seem half as surprised as she should have been by the sudden invitation for a date. At this point, my question becomes this: Is the random calls a characteristic of Holden, as a character, J.D. Salinger's writing, or the times? I wrote this on the assumption that it was a culturally sound thing to do at the time; I hope I'm correct.