What Do the VoIP Quality Test Numbers Mean?
- Upload Speed – Shown in the upper right hand corner, the upload speed is the rate at which your connection can send data. It’s usually measured in megabits per second (Mbps). This is the most important factor in the VoIP quality test, as it translates to how many phone lines you can support:
|Bandwidth (upload speed)
|Approximate Number of Lines
- Download Speed – Shown in the upper left hand corner, this is the right at which your connection can receive data. The number is probably much bigger than your upload speed. This is because home and office internet connections are optimized to download faster than they upload. In the rare instance your download speed is smaller than your upload speed, use it in the chart above instead of upload speed.
- Ping – Also called latency, this is the amount of time it takes for your computer to communicate with a server. As long as the number is below 100ms, your connection should be suited for VoIP service.
Taken together, your upload speed and download speed comprise your bandwidth. It’s the speed at which information can travel to and from your computer. For the sake of our VoIP quality test, we only have to look at the smaller of these two numbers (typically upload), as that tells you the maximum amount of data you can transfer at once, and thus how many concurrent phone calls your connection can handle.
A typical VoIP phone call requires 100 Kpbs of upload and download bandwidth. So, theoretically, if you have an upload speed of 10 Mpbs, your connection could support 100 VoIP phone calls at once. Of course this doesn’t work out in reality (the actual number is closer to 20 or 20) and that’s because of 2 specific limitations:
- Bandwidth Fluctuations. Internet speed is never completely consistent. Especially when there’s a lot of subscribers logging on in your local area, speeds can fluctuate up to 21 percent.
- Internet Browsing. Checking email, streaming videos, using web applications all take up bandwidth. Unless you have a separate, dedicated internet connection for VoIP, internet browsing will lower your bandwidth capabilities for VoIP. Fortunately, however, not by too much. Checking email, playing a YouTube video and running Spotify all at once will use up around 1 Mbps download, but only 0.25 Mpbs upload, which is the number that really matters.
We already factored bandwidth fluctuations and internet browsing into our analysis above, so you don’t have to worry about doing anything math. If you want to know the specifics, however, subtracted 105 Kpbs per line for bandwidth fluctuations and 250 Kpbs per line for internet browsing.