So, if you want to send from the Arduino to the phone the string "cool" you would have to do:
bluetoothSerial.write("cool");
bluetoothSerial.write(19);
This does the trick!
Interesting, but does that have anything to do with sending sensor readings to the phone?
I want my bluetooth to be able to send sensor readings to my phone and, if needed, for the phone to be able to send information to my Arduino.