A portable battery-powered communications device, the device being configured: to operate in a bidirectional communications mode in which voice and/or data is communicated in a bidirectional manner using a bi-directional communications protocol; and to operate in an emergency beacon mode, wherein the device is configured when in the emergency beacon mode: periodically to transmit an emergency positioning message using Bluetooth Low Energy at maximum power using the bi-directional communications protocol, wherein the emergency positioning message has a form that permits a search device to determine a bearing to the device from the search device, the transmission of the emergency positioning message defining a beacon transmit period; to listen for transmissions using the bi-directional communications protocol in a beacon response period immediately following the beacon transmit period; to enter an enhanced beacon mode in response to receiving a beacon response in the beacon response period; to operate in the enhanced beacon mode, wherein the device is configured when in the enhanced beacon mode: to transmit emergency positioning messages using Bluetooth Low Energy at intervals that are shorter than the interval between successive emergency positioning messages in the emergency beacon mode; and when in the emergency beacon mode or the enhanced beacon mode, to refrain from powering transmit and receive circuitry of the device other than during the beacon transmit period and the beacon response period. to operate in a bidirectional communications mode in which voice and/or data is communicated in a bidirectional manner using a bi-directional communications protocol; and to operate in an emergency beacon mode, wherein the device is configured when in the emergency beacon mode: periodically to transmit an emergency positioning message using Bluetooth Low Energy at maximum power using the bi-directional communications protocol, wherein the emergency positioning message has a form that permits a search device to determine a bearing to the device from the search device, the transmission of the emergency positioning message defining a beacon transmit period; to listen for transmissions using the bi-directional communications protocol in a beacon response period immediately following the beacon transmit period; to enter an enhanced beacon mode in response to receiving a beacon response in the beacon response period; to operate in the enhanced beacon mode, wherein the device is configured when in the enhanced beacon mode: to transmit emergency positioning messages using Bluetooth Low Energy at intervals that are shorter than the interval between successive emergency positioning messages in the emergency beacon mode; and periodically to transmit an emergency positioning message using Bluetooth Low Energy at maximum power using the bi-directional communications protocol, wherein the emergency positioning message has a form that permits a search device to determine a bearing to the device from the search device, the transmission of the emergency positioning message defining a beacon transmit period; to listen for transmissions using the bi-directional communications protocol in a beacon response period immediately following the beacon transmit period; to enter an enhanced beacon mode in response to receiving a beacon response in the beacon response period; to operate in the enhanced beacon mode, wherein the device is configured when in the enhanced beacon mode: to transmit emergency positioning messages using Bluetooth Low Energy at intervals that are shorter than the interval between successive emergency positioning messages in the emergency beacon mode; and when in the emergency beacon mode or the enhanced beacon mode, to refrain from powering transmit and receive circuitry of the device other than during the beacon transmit period and the beacon response period.