Method for acknowledging frames sent by endpoints in a group of endpoints intended for an application server, each endpoint in said group communicating with the application server via a gateway and a centralising server, the application server being connected to the centralising server via a first communication network, the centralising server being connected to each gateway by a second communication network, the group of endpoints and each gateway forming a third network of the long-range wireless LoRa network type affording low energy consumption, each communication between an endpoint in said group and a gateway using a communication protocol adapted to said third network, characterised in that the method is executed by the centralising server and comprises: providing, by the centralising server to each endpoint of said group, during a phase of connection to the third network implemented by said endpoint, a group identifier, receiving at least one acknowledgement message sent by the application server, each acknowledgement message acknowledging a plurality of frames sent by endpoints in said group, each acknowledgement message comprising a plurality of fields: - a first field comprising information allowing timesetting of each endpoint receiving the acknowledgement message, - a second field comprising information fixing a time of next reawakening of each endpoint receiving the acknowledgement message, - a third field comprising information representing an identifier of said group, and - a fourth field comprising information indicating, for each endpoint in said group, whether each frame that it sent to the application server since a previous acknowledgement is acknowledged; and in that the method furthermore comprises: transmitting a frame in broadcast mode to said group via each gateway making it possible to communicate with an endpoint in said group, said frame comprising, for each field of each acknowledgement message received, information representing the information represented by said field. providing, by the centralising server to each endpoint of said group, during a phase of connection to the third network implemented by said endpoint, a group identifier, receiving at least one acknowledgement message sent by the application server, each acknowledgement message acknowledging a plurality of frames sent by endpoints in said group, each acknowledgement message comprising a plurality of fields: - a first field comprising information allowing timesetting of each endpoint receiving the acknowledgement message, - a second field comprising information fixing a time of next reawakening of each endpoint receiving the acknowledgement message, - a third field comprising information representing an identifier of said group, and - a fourth field comprising information indicating, for each endpoint in said group, whether each frame that it sent to the application server since a previous acknowledgement is acknowledged; - a first field comprising information allowing timesetting of each endpoint receiving the acknowledgement message, - a second field comprising information fixing a time of next reawakening of each endpoint receiving the acknowledgement message, - a third field comprising information representing an identifier of said group, and - a fourth field comprising information indicating, for each endpoint in said group, whether each frame that it sent to the application server since a previous acknowledgement is acknowledged; and in that the method furthermore comprises: transmitting a frame in broadcast mode to said group via each gateway making it possible to communicate with an endpoint in said group, said frame comprising, for each field of each acknowledgement message received, information representing the information represented by said field.