A wireless communication method comprising: operating one or more base stations with wireless links for downlink communications with a plurality of terminals (11, 12), the one or more base stations broadcasting a trigger signal which is an emergency notification; and in response to the trigger signal, operating at least a first terminal of the plurality of terminals in a first mode in which a device-to-infrastructure, D2I, wireless link is used for uplink communications with one or more of the base stations, and operating at least a second terminal of the plurality of terminals in a second mode in which a device-to-device, D2D, wireless link is used for uplink communications, wherein the first terminal relays to a said base station, over said D2I wireless link, communications received from the second terminal via said D2D wireless link; further comprising: determining, at each terminal (11, 12), whether the terminal is a terminal in need, namely a terminal a user of which needs assistance due to the emergency; and determining, at each terminal (11, 12), whether to operate in the first mode or the second mode based on any of: - a received signal power in the downlink; - a response, or lack of response, from the base station to a D2I transmission made by the terminal; transmitting, from a terminal in need, a communication which at least identifies the terminal and its location and detecting, by a terminal operating in the first mode, the communication from the terminal in need; and relaying to the base station, from a terminal operating in the first mode, a communication detected from a terminal in need; wherein the transmitting and detecting are separated in time from the relaying, the second mode providing a time period during which the transmitting and detecting are prioritised, and/or a time period during which relaying is prioritised. operating one or more base stations with wireless links for downlink communications with a plurality of terminals (11, 12), the one or more base stations broadcasting a trigger signal which is an emergency notification; and in response to the trigger signal, operating at least a first terminal of the plurality of terminals in a first mode in which a device-to-infrastructure, D2I, wireless link is used for uplink communications with one or more of the base stations, and operating at least a second terminal of the plurality of terminals in a second mode in which a device-to-device, D2D, wireless link is used for uplink communications, wherein the first terminal relays to a said base station, over said D2I wireless link, communications received from the second terminal via said D2D wireless link; further comprising: determining, at each terminal (11, 12), whether the terminal is a terminal in need, namely a terminal a user of which needs assistance due to the emergency; and determining, at each terminal (11, 12), whether to operate in the first mode or the second mode based on any of: - a received signal power in the downlink; - a response, or lack of response, from the base station to a D2I transmission made by the terminal; - a received signal power in the downlink; - a response, or lack of response, from the base station to a D2I transmission made by the terminal; transmitting, from a terminal in need, a communication which at least identifies the terminal and its location and detecting, by a terminal operating in the first mode, the communication from the terminal in need; and relaying to the base station, from a terminal operating in the first mode, a communication detected from a terminal in need; wherein the transmitting and detecting are separated in time from the relaying, the second mode providing a time period during which the transmitting and detecting are prioritised, and/or a time period during which relaying is prioritised.