Technology Reseller - v10

01732 759725 COVER STORY 20 Quality is everything call on Broadband, including overheads. Other codes such as G729 require less bandwidth but at the expense of call quality so are not recommended for business-grade voice quality. 2 Low latency : Latency is the time it takes for a data packet to get from A to B. Latency higher than 150ms is audible and can cause cross-conversation. 3 Low jitter: Jitter is the variation in latency, with voice requiring the packets to arrive in sequence and at regular intervals. A high jitter rate above 45ms will result in corrupt audio that is extremely noticeable and off-putting to the user. 4 Low Packet loss: SIP traffic uses UDP rather than TCP. UDP is faster and better suited to voice, but lost packets are not resent. In order for a good quality call to happen, packet loss during the call needs to be as low as possible. High packet loss of more than 1% will be noticeable with words being cut and even missed entirely. What is the cost of poor voice quality? Poor call quality is not just frustrating to all concerned, it can be extremely costly through: 1 Time wasted. Each poor quality call might waste 5-10 minutes in having to repeat the call or perhaps write an email instead. How do your customer’s employees feel about poor voice quality? We have had customers who have told us that they have lost key clients as a result of previous poor SIP implementations leading to call quality problems day after day. 2 Lost business. If the poor quality call was a sales call, is there a chance that your customer is losing business as a result? What is the monetary value of each sale? £10, £100, £1,000? Perhaps more. 3 Reputation. What message does poor call quality send to existing customers? However good your product and customer service, poor call quality can create a negative image of your company’s standing. 4 Downtime. Worse than poor call quality is downtime. What are the risks of downtime? What is the cost to your business if your phones are not working? a. Would you lose sales? b. Would customers go elsewhere? c. Would you miss deadlines? d. Would your productivity drop? e. Would staff morale fall? To avoid downtime your cloud PBX service should be resilient and backed up fully with SLAs. Secondly, you must ensure that the connectivity to your service is resilient – not just to the Internet, but the entire route to your cloud PBX. This area is generally neglected! How to ensure voice quality Sadly, there isn’t a magic ‘QoS’ switch that you can flick to ensure voice quality end to end. Instead, you will need to look carefully at each component of the solution to ensure that voice quality has been considered from the start: 1 The LAN: voice traffic should be protected to ensure it isn’t compromised by normal data traffic on the LAN. This is the easy bit, and there are two main ways to ensure it: a. Create a dedicated voice LAN. This can be as simple as a dedicated voice switch into which the handsets plug via their own CAT5e/6 structured cabling. b. Apply Quality of Service (QoS) on a converged LAN. Be careful to fully understand how this will work in both directions and ensure that other sensitive traffic is not compromised. If utilising softphone apps on mobile phones over a wifi network, remember to apply QoS here as well. However, this can have a tendency to be tricky and expensive. 2 The access circuit: First, the circuit must support the technical demands of voice: a. Bandwidth: remember, this is approximately 88Kb for Ethernet or 106Kb The Cloud offers a seemingly ideal environment for deploying a voice solution but how do we ensure that the user experience is of consistently high quality? Deploying a PBX in the Cloud or utilising a Cloud based service offers many advantages: n Reduced CAPEX n Scalability/flexibility n Reduced in-house technical support requirement n Access from anywhere n Low cost & feature rich applications However, there are risks too: we have to ensure that we don’t lose focus on delivering a technically effective solution and that we offer excellent voice quality at all times. Voice Quality ISDN provides the benchmark for voice quality; indeed, it is still used for broadcasting. VoIP is too often known for poor voice quality, which might be acceptable for a conversation between friends on different continents, but is unacceptable for business. Indicators of poor voice quality calls are: n Broken audio n Calls dropping n ‘Underwater’ speech n Calls failing to connect n Echoes and crackles n ‘Tinny’ sound So what is the cause? And what can we do to provide ISDN-level quality when deploying a cloud-based VoIP solution? Technical requirements for good quality VoIP traffic There are four key technical requirements for good quality VoIP traffic, with the first often being the only one that is properly considered: 1 Sufficient bandwidth & correct codec: VoIP generally uses SIP, with G711 being the industry standard codec. The advantage of this codec is that it doesn’t compress the call and provides ISDN call quality. G711 requires 88Kb per call on Ethernet and around 106Kb per Poor voice quality might be acceptable for a conversation between friends on different continents, but is unacceptable for business Meet us at UC EXPO Stand F105 Nick Goodenough, Spitfire Partner Service Director, explains how to ensure ISDN-level voice quality when deploying a cloud-based VoIP solution Nick Goodenough