The reason you are dropping calls is due to the fact when you physically make contact with the antenna (any antenna) you disturb or change it's impedance properties. Fluctuating the impedance on an antenna causes signal propagation issues. An antenna is essentially analogous to a tuning fork, and when it is vibrating/reverberating any changes to the vibrations (i.e. an impedance fluctuation) will compromise/distort the propagated signal. If this continues long enough the tower you are communicating with will no longer know where you are and say goodbye. There is a reason this has never been done before (exposed antenna) it's a very bad design from an RF perspective. It's RF 101, and if you do a little research and take a look at other phones, you will notice that ALL cell phone antennas are galvanically isolated to some extent. It is not a firmware issue, it is an inherent design issue, line up and get your rubber bumper.