An Instructable video shows a “quick down and dirty hack” that uses a Bluetooth headset to prank callers to your cellphone with an infinite hold pattern. It involves nothing more sophisticated than a cheapo Bluetooth headset, a few components, a modicum of soldering, and some amusing tunes and message creation. Your callers will then be treated to a “you are in a XX minute queue” message and your choice of irritating music. I’m not sure what reaction I should be going with here.”]
Source: https://gizmodo.com/low-tech-bluetooth-hack-puts-callers-to-your-cellphone-5038798