An end device is essentially a reduced version of a router. This device can join existing networks and send and receive information, but cannot act as messenger between any other devices. The end device can allow other devices to join the network. It can power itself down intermittently, saving energy by temporarily entering a nonresponsive sleep mode. It always needs a router or the coordinator to be its parent device. The parent helps end devices join the network, and stores messages for them when they are asleep.