Abstract: A system obtains a second address, such as a unique IP address, from a called device by a calling device across a computer network. A first address and nick related to the called device is registered with a third device interconnected with the computer network, such as a gatekeeper, where the first address is associate with multiple devices, such as a sub-network broadcast address. The second device requests the first address from the third device by using the nick, and then initiates a first transfer of data, such as a call setup, from the second device to the first device using said first address. The first device receives the first transfer of data and in response requests a second address free from associate with said multiple devices from a fourth device, such as an address server. The first devices receives the second address from the fourth device and in response provides the second address to the second device.