Gravewood high: The Wrong Caller:

One call was a mistake.
Answering it could be deadly.
It started as a joke.
When a group of students at Gravewood High decide to call a random number using a generator app, they expect a confused stranger or a wrong number. Instead, the voice on the other end has a warning.
"You shouldn't have called."
Minutes later, the power goes out.
The doors lock And the messages begin.
Someone inside the school knows what they did and they're turning the building into a deadly game. As the night spirals into...