The FCC is calling on the top cellular carriers in the US to implement a text-to-911 system similar to that used throughout Europe, proposing a method called "over the top" messaging (uses either Wi-Fi or 3G/LET depending on what's available) similar to Apple's own Messages service. A text-to-911 service offers a number of advantages that complement traditional phone-based 911, including the ability to send silent texts in dangerous situations, aid for those who cannot speak (or speak clearly in some situations), assistance for the deaf and so on.
