Here’s the test which can help you find out if VoIP is likely to work well on your internet connection, or not. Keep in mind, internet connection quality can change at different times and for various reasons (ex: many computers being simultaneously used at the office).
How to run the test: Visualware VoIP Quality Test
1. Choose your Country
2. Choose your State
3. For “choose test type”, pick “VoIP”
4. You’ll probably need to give Java permission to run
5. Choose G.711 (64 Kbps) as your Codec
Understanding your results:
After a little bit, you’ll end up with 3 metrics which can give you a good idea of the overall call quality you can expect: Jitter, Packet Loss and MOS Score.
- Jitter should be less than 30ms for decent call quality.
- Packet loss should be as close to 0% as possible.
- MOS Score should be higher than 3.5 (approx cell phone call quality).
What is Jitter, Packet Loss and a MOS Score?
Jitter – A measure of the time interval between packets as they reach their destination. A low jitter indicates a relatively steady stream of data packets.
Packet Loss – Data, including VoIP transmission, are sent over the internet in the form of packets. Packet loss is when some of these packets do not arrive at their destination. For each packet lost, a small amount of speech will be cut out. Our brains can compensate for mild packet loss, since our brains can “fill” in the gaps. However, too much packet loss and the conversation can be very “choppy”, delayed or just sound very “unclear.”
MOS Score – The higher the MOS Score, the better your VoIP experience will be. It’s a subjective scale, ranging from 1 to 5 -with 5 representing the best possible call quality and 1 representing the worst possible call quality. The scale is based on normative data collected from experimental trials.
What if my results aren’t so great? Here’s what you can do:
- Internet speed is only part of the equation. The more computers and phones you have on your network, the faster you’ll need your connection to be. For a single VoIP line, at least 256 available kbps in each direction should be safe. Dial up won’t cut it. Satellite internet, although it has the potential to be fast, has other issues that make it less suitable for VoIP. Even with a fast connection, there can still be significant packet loss and/or high jitter, which is why bandwidth isn’t the only factor affecting call quality.
- QOS – Quality of Service. Many internet routers are able to prioritize VoIP traffic over data traffic, such as web browsing and movie streaming. VoIP requires a fairly steady stream of uninterrupted data in order to achieve good call quality. Anything that takes bandwidth away from your VoIP system can negatively impact the call quality. QOS can help to reduce this issue.
- You can also try using a different codec; one that uses less bandwidth. But generally, as you use lower bandwidth/higher compression codecs, the call quality will be negatively affected.
If you’re having problems with your VoIP, then running the above test is a good start to figuring out where the problem might be. A high quality internet connection is a very important prerequisite to having a great VoIP experience.
What do you think?
What’s been your experience with VoIP call Quality?
Have you had call quality issues? How were they resolved?
Questions or comments?