The remote line tester is a microprocessor controlled system for detecting and identifying faults in subscribers' lines and subsets over the public switched telephone network. The author describes how the system is configured, enabling it to carry out tests remotely over any transmission medium. This enables Administrations to make the most efficient use of their maintenance facilities by centralizing them at a test center. Flexibility for different applications is provided by the software, while the hardware is almost independent of the exchange type with which the remote line tester is used.