As an alternative it'd be nice to see some higher-tech GSM detection technology that allowed them to pinpoint the phones (or at least be aware of their presence).
I don't know a tremendous amount about cell towers, but I was under the impression that they couldn't very accurately pinpoint locations - I was thinking more of a [foxhunting](https://en.wikipedia.org/wiki/Transmitter_hunting)-style location, where you could (hopefully) find a phone's hiding place with relative ease.