Oswald Gerber is drowsily awoken. The telephone is ringing again. Before he climbs out of bed, he throws a quick glance at the clock: 4.00 in the morning. The last time the telephone rang was a little after 3.00. He furiously stomps through the flat and snatches the telephone receiver. “Gerber!” he shouts annoyed into the receiver. “And once you have cleaned the chicken . . .” Oswald Gerber throws the telephone down in a rage. His face is red which is due to the extreme amount of anger which is flowing through his veins. Six hours later, he is sitting opposite Criminal Inspector Hoyer who makes a short conclusion of what he has heard: “You have been called regularly for the last three nights. After you have answered the phone, a voice recites cooking recipes.”
Gerber interrupts. “Only one recipe, Mr. Inspector. The one with the…” He swallows before he can finish the sentence… “chicken”. The inspector nods, “You cannot stand chicken.” Gerber shudders, “I feel sick if someone just talks about it.” “I understand who knows about this.” “No one Mr. Inspector. That is to say, I did tell my colleagues in the finance office about it years ago. However, it is a mystery how a telephone-service is on the line when I pick the phone up.” The inspector looks at Gerber questioningly: “Are you sure that it is an official service?”
“Yes, yesterday I dialled the number of the recipe line myself. It was the same text and the same voice. Only the quality of the sound was better.”
“How long have you had a telephone connection?”
“It is exactly one week today.”
“Do your colleagues know about this?” Inspector Hoyer guessed and Gerber nodded in agreement.
“Do you believe that your colleagues have something to do with this?”
“I don’t know, Mr. Inspector. When I told them about the call after the first night, they laughed mockingly!” On the same afternoon Inspector Hoyer called in three of Gerber’s co-workers. Here are the statements of the three colleagues.
Hoffmann:
Yes, I know that Gerber has recently bought a telephone. No, we are exactly friends . . . The thing with the chicken? I can’t really remember that. I sleep like a log at night time—no, I certainly wouldn’t dally on down to the telephone box at night for Gerber’s sake.
Manning:
I am always in favour of a joke, Mr. Inspector. I remember that Gerber once told us about his chicken phobia. . Yes, I have a telephone. That’s right. I often made a few telephone jokes in the past, but we all have to grow up sometime.
Boris:
No, Mr. Inspector, I don’t own a telephone. If you ask me like that: I can’t really stand Gerber . . . What do you say about the phone calls? . . . No, it’s probably just a figment of Gerber’s imagination. Is there really a telephone service for cooking recipes?
After this questioning, the Inspector was sure that one of these three colleagues was the secret night-time caller. As he confronted the culprit with his findings, he admitted straightaway that he had been the offending caller.
Question: Who was the nightly disturbance?

Solution
The offender is called MANNING. Due to the fact that it was a tape recording, it can only have been him. Apart from this, he seemed to know all about telephone jokes.