A computing system is equipped with one or more ports, each of which includes a plurality of coupler lines configured to engage connectors that may be associated with different types of external services and/or devices, including public switched telephone networks, Ethernet networks, ISDN networks, and/or telephone devices. Upon detecting a connection to a port, a controller evaluates at least one electrical property of the lines of the port. Based on the evaluation, the controller determines if the port is engaged with a known type of service or device. When the type of service or device is known, the controller selectively switches a plurality of port lines to appropriate communications subsystems to enable the computing system to communicate with the device or service. For example, a conventional telephone device can then be used as an audio input/output device for communication over the Internet rather than over a public switched telephone network.