A wireless alarm device network comprising: a plurality of alarm devices (A-L) each comprising a processor, a wireless communication interface, and a condition sensor, the devices being adapted to communicate by wirelessly transmitting messages, wherein each device is adapted to, in a learning mode, automatically register in a monitoring cluster; and wherein each device is adapted to monitor each other device or devices in its cluster, and to generate an alert if it determines that a device in its cluster is not sending messages characterized in that each device is adapted to, in the learning mode, automatically register in a cluster according to received signal strengths, RSSI, in which it is adapted to recognise a device as being in its cluster if at least the received signal strength corresponding to the device exceeds a threshold, each device is adapted to, during the learning mode, broadcast messages and determine signal strength according to received broadcast messages, wherein during the learning mode each device is adapted to learn identifier codes of directly-communicating devices, and the devices are adapted to perform the following during the learning mode: a first device (A-L) requests a second device from which it receives messages most strongly to monitor it, the second device (A-L) accepts only if it receives messages from the first device with sufficient fade margin, if the second device accepts it registers the first device as a member of its cluster, if the first device fails to get monitoring agreement from the second device it requests a next device with the next strongest signal to monitor it, and repeats this step until it is monitored, and the other devices behave similarly until all are being monitored. a plurality of alarm devices (A-L) each comprising a processor, a wireless communication interface, and a condition sensor, the devices being adapted to communicate by wirelessly transmitting messages, wherein each device is adapted to, in a learning mode, automatically register in a monitoring cluster; and wherein each device is adapted to monitor each other device or devices in its cluster, and to generate an alert if it determines that a device in its cluster is not sending messages characterized in that each device is adapted to, in the learning mode, automatically register in a cluster according to received signal strengths, RSSI, in which it is adapted to recognise a device as being in its cluster if at least the received signal strength corresponding to the device exceeds a threshold, each device is adapted to, during the learning mode, broadcast messages and determine signal strength according to received broadcast messages, wherein during the learning mode each device is adapted to learn identifier codes of directly-communicating devices, and the devices are adapted to perform the following during the learning mode: a first device (A-L) requests a second device from which it receives messages most strongly to monitor it, the second device (A-L) accepts only if it receives messages from the first device with sufficient fade margin, if the second device accepts it registers the first device as a member of its cluster, if the first device fails to get monitoring agreement from the second device it requests a next device with the next strongest signal to monitor it, and repeats this step until it is monitored, and the other devices behave similarly until all are being monitored. a first device (A-L) requests a second device from which it receives messages most strongly to monitor it, the second device (A-L) accepts only if it receives messages from the first device with sufficient fade margin, if the second device accepts it registers the first device as a member of its cluster, if the first device fails to get monitoring agreement from the second device it requests a next device with the next strongest signal to monitor it, and repeats this step until it is monitored, and the other devices behave similarly until all are being monitored.