code: public boolean detectFirefoxOSPhone() {
  
          //First, let's make sure we're NOT on another major mobile OS.
          if (detectIos() || detectAndroid() || detectSailfish()) {
              return false;
          }
  
          if ((userAgent.indexOf(engineFirefox) != -1) && (userAgent.indexOf(mobile) != -1)) {
              return true;
          }
  
          return false;
      }
docs: Detects a phone (probably) running the Firefox OS.
  @return detection of a Firefox OS phone