Boys in movies always use walkie-talkies
In real life, nobody does this. Like, literally nobody.
It's a cheap device, and seems not to have any payoff anyway in this movie.
They establish that Jacob has means to contact people outside the house, but then almost immediately we find out that his friend is forbidden to use his walkie-talkie and it is shut off.
Later he tries to use an old-style landline phone but she turns out the power which inexplicably makes the phone not work (they don't need to be plugged in).
Carelessness, nonsense - just badly done.