A ZigBee wireless network system comprising: - a first device configured for operation in a first network, the first device comprising: - a communication interface for transmitting and receiving data over a wireless medium, - a configuration memory comprising first network configuration data enabling the first device to operate in the first network, the first network configuration data comprising a first short address within the first network by means of which another device configured for operation in the first network can address the first device in an intra-network communication mode, and - a second device configured for operation in a second network, the second device comprising - a communication interface for transmitting and receiving data over a wireless medium, - a configuration memory comprising second network configuration data enabling the second device to operate in the second network, the second network configuration data comprising a second short address within the second network by means of which another device configured for operation in the second network can address the second device in an intra-network communication mode, - said first device and said second device being configured for operation in a discovery mode, in which - said second device broadcasts a discovery message in an inter-network communication mode, - said first device upon reception of said discovery message enters a commissioning mode, in which the first device provides third network configuration data to said second device in the inter-network communication mode, the third network configuration data comprising at least a third short address within the first network, and - said second device stores said third network configuration data in its configuration memory, so that said second device is addressable in said first network in the intra-network communication mode, in addition to being addressable in said second network. - a first device configured for operation in a first network, the first device comprising: - a communication interface for transmitting and receiving data over a wireless medium, - a configuration memory comprising first network configuration data enabling the first device to operate in the first network, the first network configuration data comprising a first short address within the first network by means of which another device configured for operation in the first network can address the first device in an intra-network communication mode, and - a second device configured for operation in a second network, the second device comprising - a communication interface for transmitting and receiving data over a wireless medium, - a configuration memory comprising second network configuration data enabling the second device to operate in the second network, the second network configuration data comprising a second short address within the second network by means of which another device configured for operation in the second network can address the second device in an intra-network communication mode, - said first device and said second device being configured for operation in a discovery mode, in which - said second device broadcasts a discovery message in an inter-network communication mode, - said first device upon reception of said discovery message enters a commissioning mode, in which the first device provides third network configuration data to said second device in the inter-network communication mode, the third network configuration data comprising at least a third short address within the first network, and - said second device stores said third network configuration data in its configuration memory, so that said second device is addressable in said first network in the intra-network communication mode, in addition to being addressable in said second network.