Nice post Matt.
Several years ago the CG had a dedicated number to call while on the water and in distress. They soon found that the system did not work very well. One problem was the cell phone battery would die quickly, as stated. Another reason was that while using a radio your distress broadcast would/could be heard by other boaters who may be nearby and able to assist. If you called using a cell phone other boaters could be very near the distress vessel and have no idea that help was needed.
They stopped using the cell phone notification soon after.