1. Core VoIP Performance Metrics
- One-Way Latency: Must remain under 150 ms for natural conversations.
- Jitter: Packet delay variation must be below 20 ms.
- Packet Loss: Must remain below 1%.
- MOS (Mean Opinion Score): Target 4.2 - 4.5 for HD business voice.
2. Router QoS & DSCP Tagging
Prioritize voice packets above bulk downloads by tagging SIP signaling with DSCP CS3 (24) and RTP media with DSCP EF (46).
3. Disable SIP ALG Immediately
Router SIP ALG (Application Layer Gateway) features frequently rewrite SDP packet headers incorrectly, leading to dropped calls and one-way audio. Always disable SIP ALG on business routers.