Commissioning a network system

A wireless network system (30, 60) and a method for commissioning a wireless network system (30, 60) is described. The network system (30, 60) comprises at least a network device (1, 1′, 1″) and a joining device (21, 81, 91, 101, 111). In a commissioning mode, the network device (1, 1′, 1″) broadcasts network identification information. The joining device (21, 81, 91, 101, 111) sends, upon reception of the network identification information, a request to said network device (1, 1′, 1″) to join the network, comprising a predefined address of said joining device (21, 81, 91, 101, 111). The network device (1, 1′, 1″) assigns said joining device (21, 81, 91, 101, 111) a network address and stores corresponding data. The network device (1, 1′, 1″) sends joining information comprising at least said network address to said joining device (21, 81, 91, 101, 111) using said predefined address and said joining device (21, 81, 91, 101, 111) receives the network address, so that the joining device (21, 81, 91, 101, 111) is addressable in the network system (30, 60) using said network address.