If you're trapped by a supernatural entity, press 1
I had a fun opportunity to play the "how do we get rid of the phones" game in my WIP earlier. You know the one. It's what afflicts any novel in a modern setting where tension and a lack of help are necessary. You get to the point where the bad guy has someone holed up in a cupboard, or where things have gone seriously weird, and then you have to answer the question of why the protagonist doesn't just call the police/a friend picked at random from their address book/the local takeaway in search of help/moral support/pizza.
Generally, options include:
Poor reception at the crucial moment
"They" are watching us all through the phones
In the end, I went for a combination of one and three, in the traditional "they are watching, so get rid of the phone" routine. It occurs to me that I now have an opportunity for a complaint about the cost of the things that I haven't taken, so I'm off to write that in.