I'm revising a novel that I originally wrote in the mid-1990s. And rather than update it to modern day, I decided I needed to keep it in 1995-ish, just before the Internet invaded every last person's life, because otherwise there was no good reason for the protagonist to be unaware of a horrible thing that happened to his high school best friend. These days, you know everything that happens to your friends, former and current, because they post it on Facebook, or Tweet about it; or, if they have a modicum of privacy and dignity left, they email you personally. ("FYI, this happened...")
But back in the '90s, though we did have telephones and the post office and even, increasingly, email, we were far more able to lose track of friends--even good friends. I just don't see that happening anymore. Unless someone makes an unusual effort to stay off sites like Facebook, and is one of those people who seldom answers email--or changes their address a lot and neglects to tell their friends (and such people are regarded with large amounts of hostility from their families and acquaintances, as you know)--then you're sure to be in touch with them electronically fairly often. As to phones, nowadays everyone carries a cell, and long-distance is bundled into the monthly plan, so you don't have the excuse of cost when it comes to ringing up a friend in another state.
In short, staying in touch has become much, much easier, to the degree that I have to set stories in the grunge era if I want my characters to have startling, heartbreaking discoveries about each other and feel bad for not knowing about them sooner. Yep. Life is tough on us writers that way.