/mcpResolve Garbled Voice Problems Determine the cause of the delay and (if possible) eliminate it. Causes of drops or delays in a packet Telephony network can be many and varied. Some common examples include: Misconfigured Low Latency Queuing Misconfigured fragmentation for low speed links Misconfigured traffic shaping and/or frame relay CIR (registered customers only) exceeded Links with over-committed bandwidth in the path of the call. For example, poor CAC for voice calls. An example is a G.711 call with no cRTP or VAD across a 64 Kbps link. Duplex mismatches in an Ethernet environment CPU intensive operations on a router in the path of the call. For example, debugs to a console or saving the router configuration can cause high CPU utilization that delays packets that traverse it. It is also possible to tune the gateway de-jitter buffers for better voice performance in sub-optimal data networks. However, the results are limited to the degree to which the data network behaves correctly. For more information, refer to Troubleshooting QoS Choppy Voice Issues or a number of the documents listed at the Voice Quality Technical Support page. Hissing, Static, and Clipping These parameters identify whether VAD is used for this call and what dial peer is used: VAD = enabled PeerId=200 NoiseLevel=-59 Resolve Hissing and Clipping Problems In order to resolve hissing and some front-end clipping issues, adjust music-threshold or vad-time values (or disable VAD) before you troubleshoot other possible problems. Test by disabling comfort-noise (registered customers only) or disabling VAD entirely. If the symptom stops, then comfort noise generation is the likely cause of the problem. Reduction of the music-threshold (registered customers only) at which voice is detected or increase in the vad-time (registered customers only) values on the gateway can make the hissing or clipping less noticeable without the need to disable VAD permanently. These techniques essentially disable VAD at low volume levels and/or during small gaps, respectively. It is not practical to just disable comfort noise since that action causes other voice quality symptoms such as clicking