Abstract: Application of power to a transmitter in a messaging device is preceded by measuring a quality of at least one base station down-link signal received by a receiver in the device, and producing a transmit threshold signal when the measured signal quality corresponds to a substantial likelihood of accurate detection by a base station of an up-link signal to be transmitted from the device. The device transmitter is powered on only if the transmit threshold signal is present over a given interval prior to a transmitter operation. Thus, a relatively low-power battery and small antenna can be used effectively by the device, and its overall size kept at a minimum.