A system and method for detecting crossover faults in a telecommunications access network having a plurality of access lines. Each access line includes a pair of wires for connection to a user terminal, e.g. a telephone handset. The system includes a monitor for monitoring each of the access lines to detect the presence of an off-hook state; a current sensor for each of the access lines for determining a fault condition on an access line for which an off-hook state has been detected when a imbalance is detected between currents in the wires of the access line; a controller for generating a report of each fault condition determined on an access line, in which each report comprises a time record relating to the time of generation of the report; and a crossover fault detector for recording a possible crossover fault involving two access lines upon the reporting within a set time period of one or more fault condition on each of the two access lines.