A testing and evaluation system for efficiently qualifying individual components of a modem. A modem data pump acts as a dBm meter by measuring distortion, noise floor, and echo. The modem is coupled to a computer and a remote modem. After calibration, the remote modem may be disconnected. A resistor having a preselected resistance is coupled to the modem to allow the computer to measure the modem noise floor and distortion independent of particular telephone connections. An echo canceler coupled to the receive line allows the sum distortion and noise to be measured.