Abstract: A portable, digital processor-based system equips a craftsperson with the ability to test a subscriber line of a telephone network by accessing a direct test unit (DATU) of a telephone office, said DATU being configured to respond to commands from a telephone test set and to generate audio messages that provide the user with information relating to control of the operation of the test unit for testing a subscriber line, said portable, digital processor-based system having an input/output device, including a visual display, through which information input by the user is converted into tone signals and transmitted to said DATU, and through which information associated with the operation of said DATU is presented by said test device to the user. The displayed information is interactively updated in response to one or more inputs supplied via the input/output device by the user, irrespective of the generation of audio messages by the DATU.