Methods and apparatus for coupling outgoing analog audio signals to a subscriber line are described. One method includes the step of receiving the outgoing audio signal. The outgoing audio signal is coupled to the subscriber line through a plurality of transistors coupled in a common base configuration. In one embodiment, linefeed driver control signals for controlling battery feed to the subscriber line are received on the same signal lines as the outgoing audio signal. A subscriber line interface circuit apparatus includes a first circuit for coupling a received outgoing audio signal to a subscriber line. The first circuit couples the received outgoing audio signal to the subscriber line through a common base isolation stage. In various embodiments, the common base isolation stage comprises a plurality of bipolar junction transistors coupled in a common base configuration or a plurality of field effect transistors coupled in a common gate configuration.