Patent ID: 7095720

Claim:
Apparatus comprising: a first line interface for providing layer-1 interfacing to a communications trunk carrying a trunk signal; a first framer coupled to said first line interface providing layer-2 interfacing to said trunk signal to make available frames of multiplexed individual subscriber signals, said individual subscriber signals each including respective transmit and receive signals; a test controller coupled to said first framer for continuously de-multiplexing said frames, sampling a de-multiplexed individual transmit signal from a selected individual subscriber signal, storing said samples in a queue for a selected echo delay, adding said samples to an individual receive signal for said selected individual subscriber signal after said selected echo delay, and continuously re-multiplexing said frames; a second line interface for providing layer-1 interfacing to said communications trunk; and a second framer coupled to said test controller and said second line interface providing layer-2 interfacing to said trunk signal; wherein said first line interface said first framer, said test controller said second framer, and said second line-interface are adapted to be connected in series with said communications trunk.