Abstract: A test system for evaluating the operating state of a headend of a broadband communications network for communicating telephony signals between a telephony system and subscribers of communications services. Modulators at the headend transmit telephony signals in the forward band of the broadband communications network. The forward telephony channels are demodulated and demultiplexed by a plurality of subscriber terminals into individual telephony signals directed to an addressed subscriber. Signals returning from subscribers are digitized into standard telephony signals onto the reverse band of the broadband communications network, and demodulated by demodulators of the headend into a standard telephony signal that is interfaced to the telephony network. The test system evaluates the operating state of a selected demodulator of the headend by modulating a carrier with a predetermined data pattern to generate a upstream test signal.