Teenage daughter getting threatening calls

[areg]

My daughter has been getting threatening phone calls from a boy/boys she says she doesn’t know them. They withhold their numbers so it says no caller Id. I’ve reported it to the police online.
Does anyone know if the police can trace private numbers?

The police can't but BT can and they will if the police ask them. You could get a TrueCall device to reject unknown callers.

www.truecall.co.uk/

Change her number, then only people she knows can have it. You might find it's boys from school and her number has been shared either intentionally or accidentally. You should be able to trace the calls via your provider and the police and I don't think they would charge you for a number reallocation in the circumstances.