Oy – I hate when things like this happen.

So the other day we get a support phone call on one of our project for someone that is trying to access Second Life. Everything is working fine except voice. I.e. VOIP provided by Vivox. Normally the system works great but on occasion you get these weird one-offs.

The problem is latency. The solution is simple – upgrade to a better class of service. However that isn’t necessarily possible for everyone especially in areas only supported by satellite service. As the saying goes – may the buyer beware. In this case, not all broadband is created equal.

One of the problems is that no one publishes minimum system requirements for VOIP. So with no further ado – here are your minimum specs

  • Latency < 333 ms
  • Download Speed > 256 Kbps
  • Upload Speed > 128 Kbps

Latency and Quality of Service are your key factors. If you are on a service that is running latencies > 500ms you can forget about getting any VOIP service to work reliably. Ideally you want latencies under 100ms. 300 is high. At 500 you are pretty much out of the hunt. Routers that only support low bandwidth and do not have quality of service may also fail even if you do have minimum requirements. That is because there is no prioritization of packets and as the saying goes “your mileage may vary”.

Download speed for VOIP is usually a minimum 128 Kbps however you need to keep in mind that unless you turn everything else off, you are always going to end-up using more that the minimum. So 256 Kpbs would be considered “marginal”. Faster is obviously better.

Similar with upload speeds. You need a minimum 56 Kbps upload to run VOIP. Your system however will always be kicking out additional messages even if you aren’t running anything else. A lot of these functions there are no way to turn off (nor would you want to). So to be safe you are looking at a minimum 128 Kbps to run VOIP effectively.

So there ye be. Course the only reason I’m putting this up is because for whatever reason every gaming manufacturer that says “we run voice” like Second Life, WOW, Envoy, and a ton of other only put “broadband” up on their website for bandwidth requirements without defining exactly what they mean by broadband. In general however the rule of thumb is that if you are on basic satellite service, you are pretty much screwed due to the high latency.

When in doubt go to http://speedtest.net and see what your performance actually is. This should give you a good indication as to whether your problem is computer related or network related.

— Kevin Feenan

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