This is because the phone is designed to operate at multiple power levels so as to use only the power required to reach the network. In general, the closer you are to a wireless base station antenna, the lower the power output.
Before a phone model is available for sale to the public, it must be tested and certified to the FCC that it does not exceed the limit established by the
User Guide for the Kyocera S14 Opal phone | vii |