Abstract: A communication system includes a plurality of station sets each connected over two pair communication facilities to a control module. An adapter unit switchably connects an external data or voice device via a station set to either facility in response to a control signal from the control module. A data mode is established by sending a data mode request signal from the station set to the control module. An off-hook signal from a connected data device is used to request a data call. The control module signals to which facility the adapter is to connect the data call and outputs a unique visual on the data call facility. The control module prevents other calls from bridging onto or interfering with the data call. The system also permits a voice call on a facility to be converted to a data call on the other facility. Furthermore, a user can make a voice call over one facility while a data call is in progress on the other facility.

Abstract: A ringing signal reformatting circuit detects ringing signals having one or more ringing bursts and generates a code representing a modified distinctive ringing signal having a predetermined number of bursts and a predetermined on/off timing in response to all detected ringing signals having the same number of ringing bursts. This coded ring signal is sent to a station set and decoded thereat to generate a distinctive ring signal.