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Why should you implement QoS for VoIP?

Why should enterprises implement QoS for VoIP? Telephony expert Jon Arnold explains why QoS is vital to measure the performance of voice services.

Why should QoS be implemented in a VoIP solution?

Quality of service (QoS) is a well-established indicator of how well a telephony service or data network is living up to its promise of performance. In the case of VoIP, telephony and data performance are highly related, but QoS for VoIP is really about the telephony service.

QoS for VoIP reflects overall performance, which is impacted by several attributes, including jitter, packet loss, echo and delay. VoIP is mode of real-time communications and is highly sensitive to variations in network performance, which in turn impacts how your calls sound.

If the network is congested and there are no QoS mechanisms in place, any of the attributes above will degrade call quality. That's when you get the familiar breakdowns: calls dropping abruptly, uncomfortable delays that make conversation difficult, echo that drowns out what the other party is saying, and the stutter-stop effect of jitter that makes smooth conversation impossible.

QoS is easy to manage with TDM, since the calls run over a dedicated network and bandwidth is never an issue. But VoIP calls have to share bandwidth with all other data applications, and that's where the problems start. VoIP actually consumes very little bandwidth -- 64 Kbps -- but applications like video or file sharing can slow down the network for everything, and nothing suffers more than VoIP.

For this reason, VoIP often comes with the caveat of being a "best effort" service. Most VoIP services run over the public Internet, and when there's congestion on the LAN, or home-based employees are streaming video, VoIP is often the first casualty when bandwidth runs short. This isn't acceptable for most businesses, and for this reason, they should insist on some level of QoS assurance from their VoIP provider. Over-the-top operators that only rely on the public Internet have limited or no ability to offer QoS, and your business shouldn't rely on those services.

To get peace of mind with QoS for VoIP, it's best to partner with a VoIP provider that operates its own network and can offer service over a private data network. You'll pay more -- but still less than staying with legacy telephony. And you'll be getting QoS and won't have to worry about the hit-or-miss nature of best-effort VoIP services.

Next Steps

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