A programmable access point (110) has a line driver (201), sensors (202), comparator and control logic (203), a power supply (206), and a backup power supply (207). The line driver (201) provides power and communications signals to attached customer equipment and receives its power from either the power supply (206) or the backup power supply (207). The power supplies (206, 207) generate power supply status signals which include a signal indicating whether line driver (201) is receiving power from the power supply (206) or the backup power supply (207) and a signal indicating the reserve capacity of the backup power supply (207). The sensors (202) monitor the power output by the line driver (201). The comparator and control logic (203) receives the power supply status signals and the monitored power output values and generates a control value for line driver (201) which it provides to the line driver (201) which modifies its output responsive to the control value.