I have a pair of Cisco 3725 routers that I'm talking through using VOIP. I measured a mouth to ear delay of 70ms with a standard config. Is this what I should be getting? Is there a way to make the delay 0?
delay of 70ms
May 28, 2006
3 Replies
Are they connected by LAN or WAN? What codec and packetization period are you using? What type of voice terminal are you using?
LAN,
G.711 ulaw 20ms,
standard POTS phone
R-Guy wrote:
With 20ms packetization, it will be impossible to get less than 20ms delay, because that's how much data the gateway has to collect before sending a packet. There's also typically 10-20ms burned in the codec/DSP's pipeline. On top of that, the receiver's jitter buffer will add a few tens of ms; most jitter buffers, even adaptive ones, are tuned with a minimum of a few tens of ms because it doesn't hurt, and 40ms or so of buffering will hide all but the worst unless you have no QoS at all over a skinny WAN pipe.
70ms isn't bad, and no human should ever notice it. Don't worry about latency until it hits 150ms. SJoin the Discussion
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