Least mean power consumption in telecommunications systems

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.