Voice over IP has strict requirements. Miss them and calls become unusable.
Voice requirements:
- Latency: Under ms one-way
- Jitter: Under ms
- Packet loss: Under %
- Bandwidth: - Kbps per call (G.711)
Voice characteristics:
- Small packets (-ms audio each)
- Constant bit rate when active
- Symmetric bandwidth
QoS treatment:
- Mark with DSCP EF ()
- Place in strict priority queue
- Police to prevent flooding
- Allocate -% of bandwidth
Never let voice wait behind data. A ms delay makes conversation unusable.