Telephone system with current regulation in the constant current region

摘要

A telephone system includes a transmission line for connection to at least one telephone and a telephone interface in communication with the transmission line. The telephone interface provides DC power when a telephone connected to the transmission line is in an off-hook state. A controller in communication with the telephone interface generates a pre-defined DC characteristic of the telephone interface, and a regulator in communication with the controller adaptively translates the DC characteristic.