The present invention allows a messaging system such as a voice mail system to determine if it is connected to a property management system or some other device. If it is coupled to a property management system, the present invention allows the messaging system to determine which, if any, of several known protocols to use for communication all without the intervention of a user or administrator. In one embodiment, the invention includes determining whether a device is connected to a communications port of a messaging system, receiving a data packet at the communications port, determining a communications protocol for the received packet, and analyzing the received packet data structure. The invention further includes comparing the received packet data structure with a data structure for a known device, and if the data structure of the packet matches that for the known device determining the device coupled to the communications port to be a known device.