Look for the transmissions at far ends of the FM radio band, and at any quiet area within the FM band. If the radio begins to squeal, then slowly move it around the room until the sound become very high pitched. This is referred to as feedback detection, or loop detection and will often locate the bug.
When you call a dead phone does it ring?
Answer: A: With a dead battery it should not ring but it should go to voicemail directly.