A virtual private branch exchange (PBX) system that routes calls within a packet-switching network. Login information is received from a data device. The login information includes an alias identifying a user at the data device and a network address identifying the location of the data device on the packet-switching network. The virtual private branch exchange system associates the user's private branch exchange extension with the network address and routes calls to the user's (PBX) extension to the data device on the basis of the network address of the data device.