Call 666 and talk to the devil is an application to make a joke and a scare. It can be used to scare people, especially if they think that the person on the other side of the line is the devil himself. It can also be used to have fun with friends or family members. It's a free application, so there is no need to pay anything.

It is very easy to use. Just download the app, press the button that says "Call 666 and talk to the devil," and then you can start to call. You will be given a phone number that you will need to dial.