The mobile phone detectors we've looked at have a major problem. Because thet're passive and just sit there looking for a signal from a phone, they won't detect one unless it's a) in use or b) happens to be polling the local transmitter - which most of them only do about every half an hour ! So you can walk past the detector in the corridor and then sit next to the ICU patient having a chat on your phone - then walk back down the corridor without setting the alarm off at all.
The ICU, HDU, CCU, NNU etc staff have expressed the very strong view that they don't want these detectors actually on the ward because of the disturbance they cause when they go off !
Sometimes you just can't win.
