Everybody already went through the awful situation of been trapped in an elevator or already heard about someone who had been in this unpleasant scenario,  (this happens more than you think¹). Most elevators have an emergency phone in place that allows communication to the building’s security or the elevator’s company, or simply an emergency button. Sometimes for different reasons neither of those systems works, if no help is on the way and your call is unanswered your second option is to dial 911 on your mobile phone and is important the building has good Cellular and Public Safety signal coverage otherwise you won’t be able to complete your call. The issue is oftentimes cellular communication is not possible inside elevators ( It is important to note that Off-Air DAS systems cannot provide indoor location information during 911 calls). Any building with an elevator has multiple stories, that means layers and layers of concrete, steel, block or brick even e-glass between your phone and the cell signal source blocking and weakening the RF(Radio Frequency) signal, when you take the elevator, you are stepping inside a sort of “Faraday cage”².