I've probably told the story before of how I discovered that people who aren't sniggery 12 year olds actually call them, but just in case:
When I was a PSO, I came home to discover $housemate on the phone, describing the minor leak from his radiator. Naturally I assumed he was nagging the landlord about the state of the central heating (we were at that point heating the room with a hairdryer), but became suspicious as the conversation failed to reach any kind of plumber-related consensus, briefly went off on some other tangent, and was abruptly halted by the other party. Without missing a beat, he pressed a couple of keys and went into several iterations of "Hello, my name's [REDACTED], I'm about 6' tall, blond hair, blue eyes, if you want to chat, get back to me.".
Clarity came in a conversation with $other_housemate, who'd been in negotiations with our-favourite-telco over why they kept cutting us off. Turns out that between the student with family in ABROAD, the computer geeks[1], and the 0898[1] enthusiast, our account kept exceeding some SEEKRIT credit limit.
[1] Teenagers: Ask your parents.