Unplug the telephones.
Like peripheral devices, telephones have a cord that can be easily unplugged. Many people will fortunately assume that the telephone is dead, and not bother to check and see if the telephone is unplugged. If the owners of the telephones do not fall for the dead telephone, continue to unplug their telephones as often as possible to create impact. Unfortunately for the cleaners, they will most likely be blamed.
Telephones and their extensions are generally routed one of two ways:
- By the jack on the wall.
- By programming the telephone itself.
For extra fun try switching the configuration of telephones that are close together. Choose a time when one of the telephones owners is on vacation. It will increase the time that it takes the target to recognize that a problem exists.
For a more obvious and alarming effect, with surprisingly less effort – try changing the receiver with a telephone of a different colour. It is immediately obvious what has happened; however it defies explanation. The added benefit of this prank is the speed of execution. The replacement receiver can be sourced at any time and simply exchanged when a moment presents itself.