I happened to be reading Johnny and the Dead, and ended up at the section when the dead phone "Uncle Mad Jim". On the radio (95.3 FM in Brighton (UK), BBC Southern Counties) was the late-night phone-in, which was almost as mad as Mad Jim's, with calls ranging from people who think they're horses to randomness involving the Channel Tunnel and secret relationships to how saturday night is the busiest time for A&E, and stuff involving handcuffs, Lonely Hearts clubs, and how it is that when broadcasting internationally you shouldn't say the hour when giving the time (say "11 minutes to" not "11 minutes to 1 am"). Obviously PTerry was writing from life here.
I was tempted to to an impression of William Sticklers...
"And now over to line 2. Hello and you are?"
"You sound a bit depressed to me"
"It's worse than that. I'm dead, Jim"
Edit: it's actually BBC Southern Counties radio. That would make it Tommy Boyd's show, which runs 9pm-1am Saturdays.