A system and method for providing backup communications using Power over Ethernet (PoE) are disclosed. A backup communication system (BCS) is provided as part of a networked (TCP/IP) hospital communication system. The BCS is coupled to a power line used to provide power to a PoE switch. When TCP/IP communications are interrupted, the BCS receives patient call signals from patient room terminals over a secondary communication mode of the power line, and transmits those call signals to a nurses' station. The call signals can be generated by coupling a pulse-coded AC signal onto the PoE wires, or by sending voltage coded data in one direction and current-coded data in the other direction. Different signals or signal levels can be used to distinguish normal patient calls, patient emergency calls, and code calls. Thus, basic communications can be achieved when TCP/IP are unavailable. Other embodiments are disclosed and claimed.