The 42-year-old man in the southern city of Nuremberg was on the phone to his partner Sunday when he fell into a doze.
The woman became alarmed when he stopped speaking and called him back several times, only to get a busy signal. Then she called the police.
Fearing the worst, the emergency services dispatched a police car to the man's house, followed by the fire brigade and an ambulance.
"When the whole crew pulled up in full force, sirens blaring, the man opened the door in a daze," a police spokesman said.
The man explained the silence at his end of the line to officers at the scene: a cat-nap during a lull in the conversation.