Test set interface for automatically detecting line type

A test set interface automatically determines the type of communication link to which it is coupled, and then configures internal test circuitry to support testing of that particular type of line, irrespective of which of a plurality of different types of communication signals the line may be conveying. The interface includes a multiconductor line cord, end connections of which are configured for connection with any of multiple types of telecommunication circuits. A telecommunication circuit analysis is coupled to the line cord and to test circuitry, and is operative to analyze electrical characteristics of a respective telecommunication circuit to which the line cord is selectively connected by a test set microcontroller, so as to determine which of the different types of communication signals is being conveyed by the telecommunication circuit. In response to this determination, the test set configures its test circuitry to test the operation of the telecommunication circuit in accordance with the type of communication signal detected.