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VoIP appears to now be hitting its stride. However, VoIP still doesnt deliver the same quality and reliability with the same consistency that traditional voice delivers. In addition, with other services often being converged on the same network, QoS monitoring becomes paramount. Those that fail to stay on top of quality, service assurance, and disruptive issues are also most likely to feel the wrath of unsatisfied customers or users.
There are strong cost-reduction benefits to businesses expected in the migration from TDM voice dedicated networks to converged IP networks. There is also a concern about the capabilities of IP centric data networks being able to handle voice call loads with customer-acceptable quality. Often, network administrators are asked, Why dont we leverage our high-quality network to run our voice calls? With cost reduction being paramount in todays business world, this situation has given rise to VoIP. But adding VoIP to existing data networks is not so easy, unless such a request was anticipated, and its rarely the case.
First, one needs to distinguish the difference between Telephony over IP, where a business discards their local PBX and POTS phones and move to an IP PBX solution using IP phones. This can be a costly decision if you want to switch later. Others may prefer to keep their local PBX to manage and route calls between POTS or IP phones and route traffic over IP. This is a soft migration, which still allows the capability to use the public network, just in case.
Most people take traditional phone service for granted because businesses rarely suffer voice interruptions. In contrast, a lot of attention is being paid to the cost of disrupted data services, such as CRM, SAP, etc. Voice is just as critical a business application that is often taken for granted. Telephones, after all, are still a highly-deployed and widely used communications medium in the business world.
One may believe that to deploy VoIP a business can essentially just borrow bandwidth. But deploying VoIP only under this simple assumption can be a disaster to business goals, revenues, and customer/user retention. Trying to guess the limits and behavior that borrowed bandwidth will have on an IP network will soon lead to a lack of acceptable voice quality altogether.
Most TCP-based applications, such as e-mail, can rely on TCP to re-order or retransmit packets when one goes missing. VoIP transport does not have this luxury, because of the real time nature of voice. With VoIP, there is no retransmission, no packet reordering, and even worse, if a VoIP packet arrives too late because of congestion a very likely scenario it will be dropped, leading to choppy, cut-out, or dropped-altogether voice calls.
The Technical Due Diligence Needed for Successful VoIP
To assure that an IP network can deliver VoIP services that meet business and customer/user needs of expected quality, two fundamental questions need answering:
How much VoIP traffic will be routed? In order to get this answer you need to translate Erlangs into bandwidth, according to the Voice Codec you are going to use.
Is my overall end-to-end network delay below 100 milliseconds? Acceptable voice quality, as perceived by an end user, drops dramatically when the end to end delay exceeds 150 milliseconds.
Traffic in terms of bandwidth can be dedicated from Erlangs by making some assumptions from the following table.
The link speed is in kbps, according to the codec capabilities and the product planned for use. There might be several options to pack numerous VoIP payloads in a bigger IP frame to minimize traffic. This can come at the expense of more delay and most codecs do not support large payloads.
Getting Serious About VoIP
Businesses that are serious about what VoIP can do for their customers, efficiency, cost reductions, and revenue must be as serious about the benchmarks and tools used to plan, deploy, and continually evaluate VoIP services. There are a variety of challenges including deciding on the tools for deployment and support of VoIP services; assuring quality through service availability monitoring and service performance monitoring; and even billing considerations. There is also a complexity and diversity problem when it comes to selecting VoIP products to deploy.
Failure to tread these waters carefully and without due diligence can have a profound impact on voice communications for a business, and even an impact on the data flowing through the network. All this can lead to damaged customer loyalty for VoIP service providers, to decreased productivity for enterprises, and in the end to lost revenues and time spent dealing with VoIP problems. With careful planning, benchmarking and the right tools, business can traverse rough waters to realize new revenue streams or operational cost reductions. Businesses that try to wing it with what they have, such as by using ping-like tools or simply adding bandwidth, are destined to have VoIP problems. In the end they will have to turn to careful planning and good tools and benchmarking to get it right. So, get it right from the start and avoid the pitfalls of mismanaging VoIP services. IT
Yves Cognet is Chairman and CEO of QoSmetrics. For more information please visit the company online at www.qosmetrics.net.
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