The AM5XT and AM5eXT are microprocessor based test instruments used to measure transmission impairments on 2- and 4-wire telephone lines. The AM5XT measures transmission impairments in accordance with IEEE Standard 743-1984 (Bell Standard 41009). The AM5eXT complies with CCITT recommendations for export. The instrument also contains a separate full function signal generator able to generate the test tones normally used with the tests. The instrument contains 4 impedance selections per line, separate DC hold circuits, pulse, MF, and DTMF signaling, built-in speaker monitor and talk microphone. Optional features include RS232 remote control port, batteries for cordless portable operation, and rack mounting kit for permanent installations.