This Recommendation defines do-no-harm (DNH) tests for network-based and terminal-based voice quality enhancement (VQE) functions and non-VQE functions. These tests are applicable to functions used in both fixed and mobile networks and are independent of transport technology (e.g.@ TDM@ ATM and IP). Where necessary@ this Recommendation takes into account any similar tests that already exist in other Recommendations (e.g.@ [b-ITU-T G.160]@ [b-ITU-T G.168] and [b-ITU-T G.169]) and is applicable to both stand-alone VQE and non-VQE functions and VQE and non-VQE functions connected in tandem. Where possible@ the DNH tests defined in this Recommendation use standardized performance evaluation criteria (e.g.@ [ITU-T P.862] and [b-ITU-T P.863]) and cover all possible in-band audio signals including speech@ voiceband data and network signalling tones. Each test has a well-defined test configuration and a set of requirements that allow repeatability and consistency of results between different test laboratories. The following VQE and non-VQE functions are included in the scope for DNH: -VQE functions: ??cho cancellers including comfort noise injection ??ise reduction/cancellation functions ??utomatic gain/level control -Non-VQE functions: ??e-jitter buffers ??odecs ??oice activity detection ??ilence suppression Other functions which may be included are: -Send or ingress (entering the network): ??icrophone array processing (MAP) ??igh-frequency encoding (HFE) ??qualization (EQ) ??imiting (LM) -Receive or egress (exiting the network): ??andwidth extension (BWE) ??qualization (EQ) ??oise compensation (NC; also referred to as ALE) ??imiting (LM) This Recommendation provides guidance on how to conduct DNH testing@ including case studies@ as specific examples.