We currently have a very simple VPN from our US office to our remote office. Our bandwidth is fine, but our latency is running around 280 ms on average to the remote office. The interesting thing is that at least 70% of the time our calls are pretty good, but often we get very odd noises and dropped calls, even though the bandwidth usage and latency appear to be running at their usual baseline. Once the problem starts it seems to persist for hours at a time. Even at times when bandwidth is [much] lower than our baseline the VoIP problem can crop up.
We're not doing any VLAN tagging (we have cheap switches/routers), so QoS is likely out of the question, although I'm not sure that will help because it appears to happen at times when we have plenty of bandwidth, so I suspect that it may have something to do with our poor latency, but then why does it work well most of the time?
I'm just puzzled as to why this works so well much of the time, but some days can become unusable. Peeking with wireshark does not show anything unusual during these bad calls, so we're a bit stumped.
Any ideas or suggestions?
Thanks...***** Moderator's Note *****
Since there is no specification for minimum transit time in the IP specification, you're going to deal with latency on every VoIP call. Although 280 ms is a good figure, I'm at a loss to explain the dropouts if Wireshark doesn't show any anomaly.
If some party along the line is "traffic shaping" because they don't get paid for VoIP (and they want you to use the PSTN instead), that would explain the dropouts. I suggest you try encapsulating the VoIP calls in a VPN for some tests: the VPN will hide the traffic signature, so that might reveal if there's sabotage.
Hate to be cynical, but Comcast has been doing shaping for years (and denying it), so it's worth checking out. Please pass along the landing country(ies) as well: there might be some history.
Bill Horne Temporary Moderator
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