code: public void setSignalStrength(SignalStrength signalStrength) {
      this.signalStrength = signalStrength;
      for (PhoneStateListener listener :
          getListenersForFlags(PhoneStateListener.LISTEN_SIGNAL_STRENGTHS)) {
        listener.onSignalStrengthsChanged(signalStrength);
      }
    }
docs: Sets the value to be returned by {@link #getSignalStrength()}