Night Call, Collect is found in a collection of short stories by Ray Bradbury called I Sing the Body Electric! and can also be found in The Stories of Ray Bradbury.
This story takes place on Mars in the year 2097. Sixty years earlier, in 2037, the atomic wars started on Earth, and all people were called home from Mars to help. Emil Barton was left behind. Twenty years old, left alone on an empty planet. So, here sits Barton, eighty years old, alone for 60 years, when the phone rings. It is Barton. Twenty years old. Young Barton explains how he passed the time, living in all the houses, plenty of food and books. He began creating recordings of his voice. Set it up on timers and relays, with voice cues to allow him to have a conversation with himself.
There were a thousand voices created, put out on speakers to make it sound like there were people in towns. And then, he set up recordings, to call himself sixty years later. But it seems that young Barton was rather cruel, not realizing that he might actually still be there, the conversations not entirely friendly as he called old Barton.
This story is one that really makes you think. You have to feel sorry for a man who's been alone for a lifetime. No one to talk to but himself. And yet, maybe talking to himself wasn't such a good idea...
Here is the introduction from the NPR Broadcast. If you are interested hearing in the whole recording, you can buy it at twilightzoneradio.com, just click on the Bradbury 13 link and select the story you want.